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[bug-gsl] gsl_stats_sd_m ??? (2008-07-01)

From: "Mehdi Esteghamatian" <esteghamat@.................>
Subject: gsl_stats_sd_m ???
Date: Tue, 1 Jul 2008 09:19:33 +0430 (IRDT)
To: bug-gsl@gnu.org
Cc: mehdiesteghamat@.........

Dear bug-gsl

Hope you are all fine.

This is Mehdi Stegamatian. I am student of "Artificial Intelligence" in
Shiraz University. It is about 6 mounts that I am using GSL. I found
something which appeared to me as a bug. GSL calculates standard deviation
of single number equal to nan! Which sounds a bit vired to me. I am not a
statistician but according to my knowledge the value is zero.

I included the sample code? Could you tell me what is going on?

Best Wishes,
Mehdi

///////////////////////////////////////////////////////////////////////////////
#include <stdio.h>
#include <gsl/gsl_statistics.h>
#include <gsl/gsl_randist.h>


int main()
{
double darr[1][20];
for (int i = 0; i < 20; i++)
{
for (int j = 0; j < 1; j++)
{
darr[j][i] = i+j;
}
}

double mean = gsl_stats_mean((const double *)(darr) + 10, 20, 1);
double stddev = gsl_stats_sd_m((const double *)(darr) + 10, 20, 1, mean);

printf("mean = %f\n", mean);
printf("stddevvv = %f\n", stddev);
return 0;
}
///////////////////////////////////////////////////////////////////////////////


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