Le 15-02-11 19:48, Mike Horvath a écrit :
> On 2/11/2015 3:04 AM, Le_Forgeron wrote:
>> Le 11/02/2015 04:13, Mike Horvath a écrit :
>>> Has anyone written a function for a caternaroid(?) that works just like
>>> Paraboloid_Z in shapes_old.inc?
>>
>> I'm afraid not: Paraboloid_Z is a quadric, but a caternaroid (do you
>> mean something like a Pringles) would need something like cosh in the
>> equation.
>>
>> http://bennbatt.tumblr.com/
>>
>>   z = A.cosh(x) - B.cosh(y)
>>
>> Now, I might just be wrong, because the displayed equation
>>
>> z = x²/a² -y²/b² with x²/a²+y²/b² < 1 would be something easy on a
>> quartic, with intersection of a cylinder along z for the <1 part.
>>
>> // create a quadratic (2nd order) infinite polynomial surface
>> quadric {
>>    <1, -1, 0> //  A x^2  + B y^2  + C z^2  +
>>    <0, 0, 0> //  D xy   + E xz   + F yz   +
>>    <0, 0, -1> //  G x    + H y    + I z    +
>>    0         //  J
>> }
>>
>>
>
>
> Sorry. I meant a caternary surface of revolution. Looks almost like
> Paraboloid_Z, but a little bit different. Thanks.

It's probably closer to an hyperboloid.


Alain

Post a reply to this message