# Documentation of ttest_dan

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## Function Synopsis

[tstat, dof] = ttest(x1, x2);

## Help text

[tstat, dof] = ttest(x1, x2);
This program returns the t-statistic for a difference
in two means that should come from the same population.
The resulting t-statistic should be compared against
known charts of t-statistics, using 'dof' as the degrees
of freedom.

## Listing of function ttest_dan

function [tstat, dof] = ttest(x1, x2);
[m1, n1] = size(x1);
[m2, n2] = size(x2);
dof = m1 + m2 - 2;
sig = squeeze(sqrt( ( (m1 * (std(x1)).^2) + m2 * (std(x2)).^2 ) / dof ));
sig = sig * sqrt((1/m1) + (1/m2));
sig(find(sig == 0)) = NaN * ones(size(find(sig == 0)));
tstat = squeeze((mean(x1) - mean(x2))) ./ sig;