I think I figured out the real differences there. It's not the "power of 
ten" stuff.  After having to decide between 0.2 liters of beer or 0.3 liters 
of beer, I realized it's something different.

Imperial measurements are generally based on humans, so it's pretty 
convenient for everyday usage.

Temperature: 0 is about as cold as you're likely to run into in most places, 
100 is uncomfortably hot and basically body temperature.  50-75 is 
comfortable for the most part.

Distance: As big as your finger (inch), your foot (foot), your arms (yard), 
how far you can conveniently walk (mile).

Volume: A sip (spoonful), a mouthful (ounce), a mug full (pint), a bottle 
full (quart), a bucket full (gallon), and about as much as you can 
conveniently move by yourself (a barrel).

Weight: Again, a little bit almost unnoticeable size of a coin (ounce), 
convenient to carry in one hand (pound), convenient for weighing people or 
animals (stone, which nobody seems to actually use any more), about as much 
as you can reasonably ship someplace (a ton).

All very convenient for human scales.

But metric wins for science.

The difference with metric is that it's easy to calculate big numbers.  In 
imperial measurements, the next thing up from a mile is an AU, or a 
light-year, or a parsec (assuming you want to call these "imperial" at all). 
There's really nothing smaller than an inch, except fractions of an inch, 
and nobody goes below a 64'th of an inch. There's nothing lighter than an 
ounce, or heavier than a ton - no way to express the weight of an atom or a 
planet.

Metric has the advantage that you don't get into weird problems with units 
when you do science.  I don't think it really matters that things are 
specifically multiples of 10 until you start getting into figuring out 
ranges of numbers where exponents come into play. I'm not sure how the 
interrelatedness of the numbers matters at all: is it really useful that 
grams are defined in terms of the weight of a certain substance? I can't 
imagine how that would be useful in science, especially when things like 
"moles" and "c" are defined in terms of natural units.




In practice (for those of you who are used to metric), in every-day usage, 
imperial weird units don't really cause the sort of problem that people seem 
to think it causes. I no more have to frequently convert inches to miles 
than you frequently need to figure out the number of minutes in a year. Once 
you're talking miles, the number of inches is as immaterial as asking how 
many miles are in an inch when you're measuring to construct a chair or 
something. The worst stuff is measuring your room to be 12 3/4 feet, and 
finding out carpet is sold by the inch or something.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> I don't think it really matters that things are 
> specifically multiples of 10 until you start getting into figuring out 
> ranges of numbers where exponents come into play.

  I don't really agree with that. The metric system makes it trivial to
switch between units as needed without the need of any calculations
whatsoever.

  For example, a person can be 180 cm tall, or 1.8 meters tall, or 1 meter
80 cm tall. All three of these are completely and trivially exchangeable
with each other without the need to do any kind of mental calculations
whatsoever.

  This makes it much more intuitive and easy to quickly get a grip on
everyday measurements, as compared to familiar measurements (such as
your own height). For example, if someone tells you "the stick is 160 cm
long", then you immediately get a mental image of how long it is if you
yourself are 180 cm tall: It's something like a head less than you.

  If someone told something like "it's 2 meters tall", then once again
you can immediately grasp how much it is, compared to yourself: You know
that you are 1.8 meters tall, so 2 meters is a bit more, something like
a head taller.

  Note that two different units were used here, centimeters in the first
case and meters in the second, yet the amount of mental work to get a
notion of the length of the stick was exactly the same. No additional
mental work whatsoever was needed because two different units were used
in the two examples.

  In some cases it may be handier to use centimeters if you need that kind
of accuracy, while in other cases it's more practice to use meters because
you are not intending to be that accurate. The great thing is that in either
case it's equally easy to understand what kind of measurements we are talking
about without having to do any mental math.

  The same goes for most of the other everyday units. For example it's
easy to grasp that "516 grams" is about as heavy as a half litre of
water (because 516 grams is close to half a kilogram). Again, no mental
calculations neeed. And so on.

-- 
                                                          - Warp

Post a reply to this message

On Mon, 23 Aug 2010 15:43:54 -0400, Warp wrote:

>   I don't really agree with that. The metric system makes it trivial to
> switch between units as needed without the need of any calculations
> whatsoever.
> 
>   For example, a person can be 180 cm tall, or 1.8 meters tall, or 1
>   meter
> 80 cm tall. All three of these are completely and trivially exchangeable
> with each other without the need to do any kind of mental calculations
> whatsoever.

You're making a mental calculation there - you're dividing by 10.  It's 
easy, but that doesn't mean there's no calculation at all.

Jim

Post a reply to this message

Warp <war### [at] tagpovrayorg> wrote:
> Darren New <dne### [at] sanrrcom> wrote:
> > I don't think it really matters that things are
> > specifically multiples of 10 until you start getting into figuring out
> > ranges of numbers where exponents come into play.
>
>   I don't really agree with that. The metric system makes it trivial to
> switch between units as needed without the need of any calculations
> whatsoever.
>
>   For example, a person can be 180 cm tall, or 1.8 meters tall, or 1 meter
> 80 cm tall. All three of these are completely and trivially exchangeable
> with each other without the need to do any kind of mental calculations
> whatsoever.
>
>   This makes it much more intuitive and easy to quickly get a grip on
> everyday measurements, as compared to familiar measurements (such as
> your own height). For example, if someone tells you "the stick is 160 cm
> long", then you immediately get a mental image of how long it is if you
> yourself are 180 cm tall: It's something like a head less than you.

well put.  The thing about Imperial Units is... is it 10 of my foot or 10 of my
daughter's foot?  makes for a substantial change...

Post a reply to this message

On 23-8-2010 22:33, Jim Henderson wrote:
> On Mon, 23 Aug 2010 15:43:54 -0400, Warp wrote:
> 
>>   I don't really agree with that. The metric system makes it trivial to
>> switch between units as needed without the need of any calculations
>> whatsoever.
>>
>>   For example, a person can be 180 cm tall, or 1.8 meters tall, or 1
>>   meter
>> 80 cm tall. All three of these are completely and trivially exchangeable
>> with each other without the need to do any kind of mental calculations
>> whatsoever.
> 
> You're making a mental calculation there - you're dividing by 10.  It's 
> easy, but that doesn't mean there's no calculation at all.
> 

Oh come on, you are not dividing, just shifting the decimal point.

Post a reply to this message

On Mon, 23 Aug 2010 23:04:42 +0200, andrel wrote:

>> You're making a mental calculation there - you're dividing by 10.  It's
>> easy, but that doesn't mean there's no calculation at all.
>> 
>> 
> Oh come on, you are not dividing, just shifting the decimal point.

Which by definition, mathematically, is division (or multiplication if 
it's the other direction).

"Shifting the decimal point" isn't a recognised mathematical operation, 
well, it wasn't when I took maths.  Multiplication and division are.  
Just because one takes a shortcut doesn't mean it's a different operation.

Jim

Post a reply to this message

Jim Henderson <nos### [at] nospamcom> wrote:
> On Mon, 23 Aug 2010 23:04:42 +0200, andrel wrote:
>
> >> You're making a mental calculation there - you're dividing by 10.  It's
> >> easy, but that doesn't mean there's no calculation at all.
> >>
> >>
> > Oh come on, you are not dividing, just shifting the decimal point.
>
> Which by definition, mathematically, is division (or multiplication if
> it's the other direction).

still, it doesn't demand any calculation at all to correlate 1.80 meters to 1
meter and 80 cm or to 180 cm.  They are all equivalent, even in digits...

Post a reply to this message

On 23/08/2010 7:47 PM, Darren New wrote:
> I think I figured out the real differences there. It's not the "power of
> ten" stuff. After having to decide between 0.2 liters of beer or 0.3
> liters of beer, I realized it's something different.
>

Yes, It is what you are brought with. :-P

>
> Distance: As big as your finger (inch), your foot (foot), your arms
> (yard), how far you can conveniently walk (mile).
>

It's true then. Americans don't walk much. :-P


> Weight: Again, a little bit almost unnoticeable size of a coin (ounce),
> convenient to carry in one hand (pound), convenient for weighing people
> or animals (stone, which nobody seems to actually use any more), about
> as much as you can reasonably ship someplace (a ton).
>

We use stones for weighing people. For instance I am 12 stones but I 
would like to be 11 and a half. Or 11-7, that is 11 stones 7 pounds or 
73 Kg.


>
> There's nothing lighter than an ounce,
>

What about a dram (not a "wee dram" ;-) ) there are 16 of them in an 
ounce and 437.5 grains in an ounce.

>
>
> In practice (for those of you who are used to metric), in every-day
> usage, imperial weird units don't really cause the sort of problem that
> people seem to think it causes. I no more have to frequently convert
> inches to miles than you frequently need to figure out the number of
> minutes in a year. Once you're talking miles, the number of inches is as
> immaterial as asking how many miles are in an inch when you're measuring
> to construct a chair or something. The worst stuff is measuring your
> room to be 12 3/4 feet, and finding out carpet is sold by the inch or
> something.
>

This is true but I would measure the length to be 12' 9" or 12 foot 9 
(inches is understood).

-- 

Best Regards,
	Stephen

Post a reply to this message

> Imperial measurements are generally based on humans, so it's pretty 
> convenient for everyday usage.

So long as you don't need to convert between units or do any calculations. 
Buying carpet was one example, another is when you tell me you weigh X 
pounds and I usually deal with stones, I have no clue whether that's a lot! 
Or if you measure someones height with a tape measure marked in inches, 
what's that in feet? Or if you are following a recipe that calls for 10 oz 
of flour and you want to make 4x the quantity for a party, how much flour do 
you weigh out if your scale is in pounds and ounces?  These calculations may 
seem relatively simple if you're good at mental arithmetic, but people who 
aren't struggle (all of the ones above I've witnessed at least once).

> Metric has the advantage that you don't get into weird problems with units 
> when you do science.

Yes, it's very odd looking through an imperial science text book where every 
formula has some bizarre constant like 537.4 in it!

Post a reply to this message

scott a écrit :
>> Imperial measurements are generally based on humans, so it's pretty 
>> convenient for everyday usage.
> 
> So long as you don't need to convert between units or do any 
> calculations. Buying carpet was one example, another is when you tell me 
> you weigh X pounds and I usually deal with stones, I have no clue 
> whether that's a lot! Or if you measure someones height with a tape 
> measure marked in inches, what's that in feet? Or if you are following a 
> recipe that calls for 10 oz of flour and you want to make 4x the 
> quantity for a party, how much flour do you weigh out if your scale is 
> in pounds and ounces?  These calculations may seem relatively simple if 
> you're good at mental arithmetic, but people who aren't struggle (all of 
> the ones above I've witnessed at least once).
> 
>> Metric has the advantage that you don't get into weird problems with 
>> units when you do science.
> 
> Yes, it's very odd looking through an imperial science text book where 
> every formula has some bizarre constant like 537.4 in it!
> 
> 

Is it really any weirder than 273.15?

Likewise, I don't think 9.81 is a more convenient constant than 32.2!

My biggest beef with the imperial units is that I usually screw up the 
16th and 32nds marks on my measuring tape and end up cutting my planks 
just a little too short.  It is much harder to mix up the cm and mm lines.

-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
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/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

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> Is it really any weirder than 273.15?
>
> Likewise, I don't think 9.81 is a more convenient constant than 32.2!

Sorry I meant the unnamed numerical constants in equations, rather than the 
official named constants like 'g'.  I was just used to seeing simple 
equations in text books with no numbers in them (just symbols) yet in one of 
my books they use imperial units and almost every equation has some 
numerical constant in it.  On top of that they find it necessary to write 
the units needed for every quantity, which I guess have to tie up with the 
constant.  It just looks messy (and presumably quite hard to remember), 
that's all.

Post a reply to this message

On 8/23/2010 10:53 PM, Jim Henderson wrote:
> "Shifting the decimal point" isn't a recognised mathematical operation,
> well, it wasn't when I took maths.  Multiplication and division are.
> Just because one takes a shortcut doesn't mean it's a different operation.

Shifts are perfectly legitimate mathematical operations. Many of the 
things computers do couldn't be done easily without a shift operation :P

-- 
~Mike

Post a reply to this message

Stephen wrote:
> It's true then. Americans don't walk much. :-P

Well, I mean, there's a small multiple right? It's not like you can only 
drink one pint of beer, either. :-)  Walking somewhere between 0.1 and 10 
miles is convenient. Outside that, you're going to measure in yards or 
you're going to take a horse.

> We use stones for weighing people. For instance I am 12 stones but I 
> would like to be 11 and a half. Or 11-7, that is 11 stones 7 pounds or 
> 73 Kg.

Cool. Where is this?

>> There's nothing lighter than an ounce,
> 
> What about a dram (not a "wee dram" ;-) ) there are 16 of them in an 
> ounce and 437.5 grains in an ounce.

I wasn't sure if a dram was imperial or not.

> This is true but I would measure the length to be 12' 9" or 12 foot 9 
> (inches is understood).

Yes, exactly. The construction rulers here measure in both inches and feet, 
so it's trivial to get either measurement in situations where people use 
both scales.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

Post a reply to this message

On Tue, 24 Aug 2010 08:41:13 -0500, Mike Raiford wrote:

> On 8/23/2010 10:53 PM, Jim Henderson wrote:
>> "Shifting the decimal point" isn't a recognised mathematical operation,
>> well, it wasn't when I took maths.  Multiplication and division are.
>> Just because one takes a shortcut doesn't mean it's a different
>> operation.
> 
> Shifts are perfectly legitimate mathematical operations. Many of the
> things computers do couldn't be done easily without a shift operation :P

Binary shifts are multiplication and division as well. :P

Jim

Post a reply to this message

On Tue, 24 Aug 2010 02:05:56 -0400, nemesis wrote:

> Jim Henderson <nos### [at] nospamcom> wrote:
>> On Mon, 23 Aug 2010 23:04:42 +0200, andrel wrote:
>>
>> >> You're making a mental calculation there - you're dividing by 10. 
>> >> It's easy, but that doesn't mean there's no calculation at all.
>> >>
>> >>
>> > Oh come on, you are not dividing, just shifting the decimal point.
>>
>> Which by definition, mathematically, is division (or multiplication if
>> it's the other direction).
> 
> still, it doesn't demand any calculation at all to correlate 1.80 meters
> to 1 meter and 80 cm or to 180 cm.  They are all equivalent, even in
> digits...

But not in decimal points.  It's still division/multiplication by 10, no 
matter how you describe how it looks.

Jim

Post a reply to this message

>> Shifts are perfectly legitimate mathematical operations. Many of the
>> things computers do couldn't be done easily without a shift operation :P
> 
> Binary shifts are multiplication and division as well. :P

What you want is binary rotations. ;-)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

On 24/08/2010 2:56 PM, Darren New wrote:
> Stephen wrote:
>> It's true then. Americans don't walk much. :-P
>
> Well, I mean, there's a small multiple right? It's not like you can only
> drink one pint of beer, either. :-) Walking somewhere between 0.1 and 10
> miles is convenient. Outside that, you're going to measure in yards or
> you're going to take a horse.
>

Just pulling your leg Cuz. ;-)

>> We use stones for weighing people. For instance I am 12 stones but I
>> would like to be 11 and a half. Or 11-7, that is 11 stones 7 pounds or
>> 73 Kg.
>
> Cool. Where is this?
>

Here's a clue
http://tinyurl.com/6zz4l7

>>> There's nothing lighter than an ounce,
>>
>> What about a dram (not a "wee dram" ;-) ) there are 16 of them in an
>> ounce and 437.5 grains in an ounce.
>
> I wasn't sure if a dram was imperial or not.

It has a crown, does it not? :-)

>
>> This is true but I would measure the length to be 12' 9" or 12 foot 9
>> (inches is understood).
>
> Yes, exactly. The construction rulers here measure in both inches and
> feet, so it's trivial to get either measurement in situations where
> people use both scales.
>

We're going metric and have rulers with inches on one edge and 
centimetres on the other. (Rotated 180 degrees so you can't do a direct 
comparison/conversion.)

-- 

Best Regards,
	Stephen

Post a reply to this message

Stephen wrote:
> Here's a clue
> http://tinyurl.com/6zz4l7

I don't know. That doesn't do anything except give me a blank page.

> We're going metric and have rulers with inches on one edge and 
> centimetres on the other. (Rotated 180 degrees so you can't do a direct 
> comparison/conversion.)

Yeah, that's how our measuring tapes are too. Except the inches side has 
both feet+inches and inches.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

Post a reply to this message

Stephen wrote:
> Here's a clue
> http://tinyurl.com/6zz4l7

Oh, it downloaded a MP3. OK. Nevermind. Very cute.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

Post a reply to this message

On 24-8-2010 18:11, Jim Henderson wrote:
> On Tue, 24 Aug 2010 08:41:13 -0500, Mike Raiford wrote:
> 
>> On 8/23/2010 10:53 PM, Jim Henderson wrote:
>>> "Shifting the decimal point" isn't a recognised mathematical operation,
>>> well, it wasn't when I took maths.  Multiplication and division are.
>>> Just because one takes a shortcut doesn't mean it's a different
>>> operation.
>> Shifts are perfectly legitimate mathematical operations. Many of the
>> things computers do couldn't be done easily without a shift operation :P
> 
> Binary shifts are multiplication and division as well. :P

yes and no. Conceptually yes, in a hardware implementation on a chip no.
That is why they are so much cheaper than real multiplicatons and 
division. The same goes for wetware. But I appreciate your stubbornness.

Post a reply to this message

On Tue, 24 Aug 2010 17:18:01 +0100, Orchid XP v8 wrote:

>>> Shifts are perfectly legitimate mathematical operations. Many of the
>>> things computers do couldn't be done easily without a shift operation
>>> :P
>> 
>> Binary shifts are multiplication and division as well. :P
> 
> What you want is binary rotations. ;-)

That depends on whether the bits actually get rotated.  From my 
recollection of x86 assembly, it's a shift, not a rotation. :)

Jim

Post a reply to this message

On Tue, 24 Aug 2010 21:21:53 +0200, andrel wrote:

> On 24-8-2010 18:11, Jim Henderson wrote:
>> On Tue, 24 Aug 2010 08:41:13 -0500, Mike Raiford wrote:
>> 
>>> On 8/23/2010 10:53 PM, Jim Henderson wrote:
>>>> "Shifting the decimal point" isn't a recognised mathematical
>>>> operation, well, it wasn't when I took maths.  Multiplication and
>>>> division are. Just because one takes a shortcut doesn't mean it's a
>>>> different operation.
>>> Shifts are perfectly legitimate mathematical operations. Many of the
>>> things computers do couldn't be done easily without a shift operation
>>> :P
>> 
>> Binary shifts are multiplication and division as well. :P
> 
> yes and no. Conceptually yes, in a hardware implementation on a chip no.
> That is why they are so much cheaper than real multiplicatons and
> division. The same goes for wetware. 

That still doesn't mean it isn't mathematically a multipilcation or 
division - the operation doesn't change just because you took a 
shortcut. ;-)

> But I appreciate your stubbornness.

I figured you - of all people - would. ;-)

Jim

Post a reply to this message

andrel wrote:
> That is why they are so much cheaper than real multiplicatons and 
> division. 

If you're using a compiler where a shift by a constant is cheaper than a 
division by a constant, you're in trouble.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

Post a reply to this message

On Tue, 24 Aug 2010 15:33:19 -0400, Jim Henderson wrote:

> On Tue, 24 Aug 2010 17:18:01 +0100, Orchid XP v8 wrote:
> 
>>>> Shifts are perfectly legitimate mathematical operations. Many of the
>>>> things computers do couldn't be done easily without a shift operation
>>>> :P
>>> 
>>> Binary shifts are multiplication and division as well. :P
>> 
>> What you want is binary rotations. ;-)
> 
> That depends on whether the bits actually get rotated.  From my
> recollection of x86 assembly, it's a shift, not a rotation. :)
> 
> Jim

My recollection, of course, has changed now that I re-read this, I 
remember ROR and ROL operators, which do in fact rotate.  I just remember 
using SHL and SHR more frequently.

Jim

Post a reply to this message

>>>> Binary shifts are multiplication and division as well. :P
>>> What you want is binary rotations. ;-)
>> That depends on whether the bits actually get rotated.  From my
>> recollection of x86 assembly, it's a shift, not a rotation. :)
>>
>> Jim
> 
> My recollection, of course, has changed now that I re-read this, I 
> remember ROR and ROL operators, which do in fact rotate.  I just remember 
> using SHL and SHR more frequently.

Whether your processor supports it or not, binary rotations exist. You 
can implement them the hard way if you must. I've seen a few block 
ciphers that use 'em too...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

On 24/08/2010 7:33 PM, Darren New wrote:
> Stephen wrote:
>> Here's a clue
>> http://tinyurl.com/6zz4l7
>
> Oh, it downloaded a MP3. OK. Nevermind. Very cute.
>

Cute, that's me :-)

-- 

Best Regards,
	Stephen

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> andrel wrote:
> > That is why they are so much cheaper than real multiplicatons and 
> > division. 

> If you're using a compiler where a shift by a constant is cheaper than a 
> division by a constant, you're in trouble.

  He was talking about hardware, not about compilers.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> andrel wrote:
>>> That is why they are so much cheaper than real multiplicatons and 
>>> division. 
> 
>> If you're using a compiler where a shift by a constant is cheaper than a 
>> division by a constant, you're in trouble.
> 
>   He was talking about hardware, not about compilers.

Yes, I knew that. :-)

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

Post a reply to this message

On 24-8-2010 21:34, Jim Henderson wrote:
> On Tue, 24 Aug 2010 21:21:53 +0200, andrel wrote:
> 
>> On 24-8-2010 18:11, Jim Henderson wrote:
>>> On Tue, 24 Aug 2010 08:41:13 -0500, Mike Raiford wrote:
>>>
>>>> On 8/23/2010 10:53 PM, Jim Henderson wrote:
>>>>> "Shifting the decimal point" isn't a recognised mathematical
>>>>> operation, well, it wasn't when I took maths.  Multiplication and
>>>>> division are. Just because one takes a shortcut doesn't mean it's a
>>>>> different operation.
>>>> Shifts are perfectly legitimate mathematical operations. Many of the
>>>> things computers do couldn't be done easily without a shift operation
>>>> :P
>>> Binary shifts are multiplication and division as well. :P
>> yes and no. Conceptually yes, in a hardware implementation on a chip no.
>> That is why they are so much cheaper than real multiplicatons and
>> division. The same goes for wetware. 
> 
> That still doesn't mean it isn't mathematically a multipilcation or 
> division - the operation doesn't change just because you took a 
> shortcut. ;-)

that is what I said, or at least tried to.

>> But I appreciate your stubbornness.
> 
> I figured you - of all people - would. ;-)

we aim to please

Post a reply to this message

On 25-8-2010 17:28, Darren New wrote:
> Warp wrote:
>> Darren New <dne### [at] sanrrcom> wrote:
>>> andrel wrote:
>>>> That is why they are so much cheaper than real multiplicatons and 
>>>> division. 
>>
>>> If you're using a compiler where a shift by a constant is cheaper 
>>> than a division by a constant, you're in trouble.
>>
>>   He was talking about hardware, not about compilers.
> 
> Yes, I knew that. :-)
> 
Even so I do not understand the remark. Do you mean that a compiler 
should not be aware what is cheaper (in time) to do the same thing? Or 
that that is not the case anymore, in which case I beg to differ.

Post a reply to this message

On Wed, 25 Aug 2010 10:28:25 +0100, Orchid XP v8 wrote:

>>>>> Binary shifts are multiplication and division as well. :P
>>>> What you want is binary rotations. ;-)
>>> That depends on whether the bits actually get rotated.  From my
>>> recollection of x86 assembly, it's a shift, not a rotation. :)
>>>
>>> Jim
>> 
>> My recollection, of course, has changed now that I re-read this, I
>> remember ROR and ROL operators, which do in fact rotate.  I just
>> remember using SHL and SHR more frequently.
> 
> Whether your processor supports it or not, binary rotations exist. You
> can implement them the hard way if you must. I've seen a few block
> ciphers that use 'em too...

Well, that's why I said what I said about my faulty recollection. ;-)

Jim

Post a reply to this message

On 8/23/2010 2:47 PM, Darren New wrote:

> Metric has the advantage that you don't get into weird problems with
> units when you do science. I don't think it really matters that things
> are specifically multiples of 10 until you start getting into figuring
> out ranges of numbers where exponents come into play.

If you've taken physics, the real help comes in the fact that the 
majority of units are some multiple of other units with no other factors 
to throw in (and thus, misremembered at times).

For example, one Watt (unit of power) is equal to one Joule (unit of 
energy) per second.  One horsepower (imperial unit of power) is equal to 
some silly number of foot-pounds per second.

Regards,
John

Post a reply to this message

John VanSickle wrote:
> For example, one Watt (unit of power) is equal to one Joule (unit of 
> energy) per second.  One horsepower (imperial unit of power) is equal to 
> some silly number of foot-pounds per second.

Sure. That comes from having only one unit of measurement for each 
fundamental thing you're measuring. On the other hand, you still get some 
arbitrary factors in there, like moles or parsecs.

If I asked you how much power it took to lift what a horse could, or how 
many pounds of force you had to push a foot-long lever with, you'd once 
again have those arbitrary scale factors thrown in. ;-)

I'm not saying metric isn't easier. I'm pointing out that imperial stuff, 
since it's based on people, is very poor at measuring things that aren't 
approximately relevant to people, like the weight of planets or the size of 
atoms.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

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Darren New <dne### [at] sanrrcom> wrote:
> I'm not saying metric isn't easier. I'm pointing out that imperial stuff,
> since it's based on people, is very poor at measuring things that aren't
> approximately relevant to people, like the weight of planets or the size of
> atoms.

It's not just that: imperial isn't precise.  I asked before and it was ignored,
but should I measure 10 foot to be the distance traveled by my 10 of my steps or
10 of my daughter steps?

Besides, you need to put true mental calculations at work to convert between
units, instead of simply moving the point forward or backwards between
centimeters, meters and kilometers...

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nemesis wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> I'm not saying metric isn't easier. I'm pointing out that imperial stuff,
>> since it's based on people, is very poor at measuring things that aren't
>> approximately relevant to people, like the weight of planets or the size of
>> atoms.
> 
> It's not just that: imperial isn't precise.  I asked before and it was ignored,

Well, *now* it is precise. Obviously it wasn't precise when it was 
formulated.  I think the foot, however, was the size of some specific king's 
foot. And the metric measurements have changed definitions over the years as 
well.

> Besides, you need to put true mental calculations at work to convert between
> units, instead of simply moving the point forward or backwards between
> centimeters, meters and kilometers...

Sure, because there are different units, unlike the SI measurements which 
only have one unit per fundamental element being measured. I still have to 
put mental calculations forth to translate between seconds and meters, or 
between meters and light-years, or between watt-hours and watt-months, or 
between moles and grams, because they're different units based on arbitrary 
physical properties. The fact that one has to translate between inches and 
feet isn't really any more of a problem than the fact that metric 
measurements have to translate between seconds and years.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

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On 29/08/2010 12:53 AM, Darren New wrote:
>
> Well, *now* it is precise. Obviously it wasn't precise when it was
> formulated.  I think the foot, however, was the size of some specific
> king's foot. And the metric measurements have changed definitions over
> the years as well.
>

Henry I of England, but not his bare foot.

>> Besides, you need to put true mental calculations at work to convert
>> between
>> units, instead of simply moving the point forward or backwards between
>> centimeters, meters and kilometers...
>
> Sure, because there are different units, unlike the SI measurements
> which only have one unit per fundamental element being measured. I still
> have to put mental calculations forth to translate between seconds and
> meters, or between meters and light-years, or between watt-hours and
> watt-months, or between moles and grams, because they're different units
> based on arbitrary physical properties. The fact that one has to
> translate between inches and feet isn't really any more of a problem
> than the fact that metric measurements have to translate between seconds
> and years.

I would say less of a problem, actually. Constantly doing mental 
arithmetic helps keep the mind active. I’ve noticed, here in the UK, the 
lack of ability in young people who grew up learning the metric system. 
I assume that they did not have to do sums like:
What is the cost of 3 yards 1 foot of material @ 2/6 a yard.

Ans: 8/4 That is 8 shillings and 4 pence.

-- 

Best Regards,
	Stephen

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Le 29/08/2010 11:17, Stephen nous fit lire :
> On 29/08/2010 12:53 AM, Darren New wrote:
>>
>> Well, *now* it is precise. Obviously it wasn't precise when it was
>> formulated.  I think the foot, however, was the size of some specific
>> king's foot. And the metric measurements have changed definitions over
>> the years as well.
>>
> 
> Henry I of England, but not his bare foot.
> 
>>> Besides, you need to put true mental calculations at work to convert
>>> between
>>> units, instead of simply moving the point forward or backwards between
>>> centimeters, meters and kilometers...
>>
>> Sure, because there are different units, unlike the SI measurements
>> which only have one unit per fundamental element being measured. I still
>> have to put mental calculations forth to translate between seconds and
>> meters, or between meters and light-years, or between watt-hours and
>> watt-months, or between moles and grams, because they're different units
>> based on arbitrary physical properties. The fact that one has to
>> translate between inches and feet isn't really any more of a problem
>> than the fact that metric measurements have to translate between seconds
>> and years.
> 
> I would say less of a problem, actually. Constantly doing mental
> arithmetic helps keep the mind active. I’ve noticed, here in the UK, the
> lack of ability in young people who grew up learning the metric system.
> I assume that they did not have to do sums like:
> What is the cost of 3 yards 1 foot of material @ 2/6 a yard.
> 
> Ans: 8/4 That is 8 shillings and 4 pence.
> 

Why stop at only mental activity, let's also take into account the year
of mint, as it used to be.
And each mint (and that could each city) could have its own agenda for
the weight of its pounds & guinea.

May be I can slice some pounds in two, or scrap enough of them to make a
new one...

Shilling has been dropped in 1971... and the penny is now decimal.
But we can mix pound, shilling (at 20 per pound), pences (at 240 per
pound) and new pences (at 100 per pound) with guinea (1 pound 1 shilling)

Oh, I call in the Bretton Woods system, in which I could exchange 1
pounds for $4.03...

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On 29/08/2010 10:49 AM, Le_Forgeron wrote:
> Why stop at only mental activity, let's also take into account the year
> of mint, as it used to be.
> And each mint (and that could each city) could have its own agenda for
> the weight of its pounds&  guinea.
>

Now you are being silly. ;-)

> May be I can slice some pounds in two, or scrap enough of them to make a
> new one...
>

That is why coins are milled. To stop people like you shaving or 
clipping coins. :-P

> Shilling has been dropped in 1971... and the penny is now decimal.
> But we can mix pound, shilling (at 20 per pound), pences (at 240 per
> pound) and new pences (at 100 per pound) with guinea (1 pound 1 shilling)
>

But some of us remember the days of L.s.d. man ;-)

> Oh, I call in the Bretton Woods system,

Morning town Crescent!

> in which I could exchange 1
> pounds for $4.03...

I remember my father calling a half crown (12.5p) a half dollar.

-- 

Best Regards,
	Stephen

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Le_Forgeron wrote:
> And each mint (and that could each city) could have its own agenda for
> the weight of its pounds & guinea.

Well, yes. There's also the problem with imperial measures that the king 
would go around declaring that a barrel in London is somewhat larger than a 
barrel outside of London, thereby lowering the cost of beer in the capital 
city and stuff like that.

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

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On 29-8-2010 1:53, Darren New wrote:
> nemesis wrote:
>> Darren New <dne### [at] sanrrcom> wrote:
>>> I'm not saying metric isn't easier. I'm pointing out that imperial 
>>> stuff,
>>> since it's based on people, is very poor at measuring things that aren't
>>> approximately relevant to people, like the weight of planets or the 
>>> size of
>>> atoms.
>>
>> It's not just that: imperial isn't precise.  I asked before and it was 
>> ignored,
> 
> Well, *now* it is precise. Obviously it wasn't precise when it was 
> formulated.  I think the foot, however, was the size of some specific 
> king's foot. And the metric measurements have changed definitions over 
> the years as well.

Such changes occur for good reasons. E.g. in the triple 
time/velocity/length you can define any two and the third can then be 
measured. Originally the speed of light was the quantity to measure. 
Nowadays that is a constant, otherwise the theoretical physicists would 
be very upset.
If you define the length then you can measure how long one second is. Or 
you define a meter and then you can measure how much time a photon takes 
to traverse that distance. Which one you choose simply depends on what 
you can measure most accurately. If your error in a meter is, say, one 
in 10^12 and in a second it is one in 10^10, it is unwise to take the 
second as definition, because the maximal achievable precision of a 
length measurement will then drop to one in 10^10.

I hope all imperial units are now defined as fractions of the metric 
ones or we will need two committees to decide when to change the places 
of meters and seconds. However, if you look at the wiki page about 
imperial units some conversions are exact, whereas others are given to 
be exact to 4 or 5 decimal places. Much larger than the scientific 
uncertainty in the values, so that supports nemesis' claim, although 
perhaps not in the way he/she meant.

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On 29/08/2010 5:48 PM, Darren New wrote:
> Le_Forgeron wrote:
>> And each mint (and that could each city) could have its own agenda for
>> the weight of its pounds & guinea.
>
> Well, yes. There's also the problem with imperial measures that the king
> would go around declaring that a barrel in London is somewhat larger
> than a barrel outside of London, thereby lowering the cost of beer in
> the capital city and stuff like that.
>

LOL, not quite, declaring that a barrel in London is somewhat larger 
than a barrel outside of London, thereby getting more tax and making it 
dearer.

-- 

Best Regards,
	Stephen

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On Sun, 29 Aug 2010 16:55:35 +0100, Stephen wrote:

>> Oh, I call in the Bretton Woods system,
> 
> Morning town Crescent!

No, you can't do that, because it's the 29th of the month, so diagonals 
are not allowed... ;-)

Jim

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On 29/08/2010 6:57 PM, Jim Henderson wrote:
> On Sun, 29 Aug 2010 16:55:35 +0100, Stephen wrote:
>
>>> Oh, I call in the Bretton Woods system,
>>
>> Morning town Crescent!
>
> No, you can't do that, because it's the 29th of the month, so diagonals
> are not allowed... ;-)
>

But using the “Bretton Woods system” allows me to move in a chess knight 
like manner.

BTW Humph Celebration Concert tomorrow
http://www.bbc.co.uk/programmes/b00tj5qp
If you can’t get it I’ll record it if it’s on listen again.

-- 

Best Regards,
	Stephen

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andrel wrote:
> On 29-8-2010 1:53, Darren New wrote:
> Such changes occur for good reasons. 

Of course.

> I hope all imperial units are now defined as fractions of the metric 

Honestly, I have no idea. I know they're more precise than the size of some 
king's shoe or how far Fred can march in 15 minutes.

> the wiki page about imperial units s

Wow. That's messier than I thought. ;-)

-- 
Darren New, San Diego CA, USA (PST)
    Quoth the raven:
        Need S'Mores!

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On Sun, 29 Aug 2010 19:10:24 +0100, Stephen wrote:

> On 29/08/2010 6:57 PM, Jim Henderson wrote:
>> On Sun, 29 Aug 2010 16:55:35 +0100, Stephen wrote:
>>
>>>> Oh, I call in the Bretton Woods system,
>>>
>>> Morning town Crescent!
>>
>> No, you can't do that, because it's the 29th of the month, so diagonals
>> are not allowed... ;-)
>>
>>
> But using the “Bretton Woods system” allows me to move in a chess knight
> like manner.

Not in the last week of the month, though.  And you thought you could 
sneak that past me. ;-)

> BTW Humph Celebration Concert tomorrow
> http://www.bbc.co.uk/programmes/b00tj5qp If you can’t get it I’ll record
> it if it’s on listen again.

Cool, I should be able to get it from listen again (I've been pulling 
Proms concerts that way), but if I can't, I'll let you know.

Jim

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On 30/08/2010 6:25 PM, Jim Henderson wrote:
> Cool, I should be able to get it from listen again (I've been pulling
> Proms concerts that way), but if I can't, I'll let you know.
>

OK, I downloaded it from listen again. A bit too much jazz for my liking.

-- 

Best Regards,
	Stephen

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On Mon, 30 Aug 2010 23:23:55 +0100, Stephen wrote:

> On 30/08/2010 6:25 PM, Jim Henderson wrote:
>> Cool, I should be able to get it from listen again (I've been pulling
>> Proms concerts that way), but if I can't, I'll let you know.
>>
>>
> OK, I downloaded it from listen again. A bit too much jazz for my
> liking.

I'm pulling it now, so no need to keep it if you don't want to. :-)

Jim

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On 31/08/2010 2:59 AM, Jim Henderson wrote:
> I'm pulling it now, so no need to keep it if you don't want to.:-)
>


Tickety boo

-- 

Best Regards,
	Stephen

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On Tue, 31 Aug 2010 17:05:14 +0100, Stephen wrote:

> On 31/08/2010 2:59 AM, Jim Henderson wrote:
>> I'm pulling it now, so no need to keep it if you don't want to.:-)
>>
>>
> 
> Tickety boo

We really enjoyed it - but we also enjoy good Jazz.  :-)

Jim

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On 03/09/2010 11:23 PM, Jim Henderson wrote:
> but we also enjoy good Jazz.:-)

There is such a thing? :-)

-- 

Best Regards,
	Stephen

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