     POV-Ray : Newsgroups : povray.advanced-users : Problems using/graphing internal sum function : Problems using/graphing internal sum function Server Time29 Jan 2023 07:43:55 EST (-0500) Problems using/graphing internal sum function   From: Bald Eagle Date: 7 Nov 2022 19:50:00 Message:    ```
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"headline": "Problems using\/graphing internal sum function",
"dateCreated": "2022-11-08T00:50:00+00:00",
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Something popped into my head recently, and now I am trying to write an equation
for the cumulative distribution function of a probability density function using
sum ().

I'm using a normal distribution, but when I try to graph the summation of the
values over the range of 0 through 5, I get unexpected results.

I tried using N, then since i is related to N, I tried seeing what that result
looked like, and then I averaged them...  It makes no sense that a graph of a
running tally starts to decrease, instead of being non-decreasing and
right-continuous like it should be.

#declare NDist = function (N, mu, sigma)
{1/(sigma*sqrt(tau))*exp(-0.5*pow((N-mu)/sigma,2))}

#declare NDist_cdf = function (N, mu, sigma) {sum (i, 0, N, NDist (N, mu,
sigma))}

#declare NDist_cdf2 = function (N, mu, sigma) {sum (i, 0, N, NDist (i, mu,
sigma))}

#declare NDist_cdf3 = function (N, mu, sigma) {sum (i, 0, N, NDist ((i+N)/2,
mu, sigma))}

Has anyone ever tried to use sum () to graph a running tally of a function, or
have any idea what I'm doing wrong?

Have I broken POV-Ray _*AGAIN*_???!
```

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