<OT> unix math function: norm

[Joel Hammer]

Oh well.

I messed around with norm. It looks like it just gives the cumulative
frequency, which doesn't help.

So, I programmed gnuplot to give the Gaussian frequency for any given
x,u,and variance. It seems to work.

If anyone cares, here it is:

f(x)=exp(-((x-u)**2/(2*var)))/(sqrt(2*pi*var)) 

where var and u are calculated elsewhere in the program.

BTW, the link below gives the wrong formula for the Gaussian frequency, as best as
I can tell.

http://csep1.phy.ornl.gov/mc/node19.html

It has the standard deviation inside the square root sign in the
denominator. It should be outside. So, I guess you shouldn't trust stuff you
download.

Joel


On Sat, May 25, 2002 at 09:15:38AM -0400, Joel Hammer wrote:
> I am using gnuplot. I want to have bar graphs of data with a superimposed
> Gaussian distribution, based on the usual mean and standard deviation
> that the typical spreadsheet calculates from the data.  There is a
> function called norm in the gnuplot program which sounds like this is
> what I need. However, here is all the manual has to say:
> 
>   The norm function returns the normal distribution function (or Gaussian)
>   of the real part of its argument.
> 
> and
> 
>   The functions in GNUPLOT are the same as the corresponding functions
>   in the Unix math library, except that all functions accept integer,
>   real, and complex arguments, unless otherwise noted.
> 
> 
> I have looked for the unix math manual on line, and can't find one. Could someone
> please explain how to use the norm function in unix, or better yet, in
> gnuplot?
> 
> Thanks,
> Joel
> 
> 
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