For two samples x and y from normal distributions with unknown means and unknown equal variances, perform a two-sample t-test of the null hypothesis of equal means. Under the null, the test statistic t follows a Student distribution with df degrees of freedom.
With the optional argument string alt, the alternative of interest can be selected. If alt is
"!="or"<>", the null is tested against the two-sided alternativemean (x) != mean (y). If alt is">", the one-sided alternativemean (x) > mean (y)is used. Similarly for"<", the one-sided alternativemean (x) < mean (y)is used. The default is the two-sided case.The p-value of the test is returned in pval.
If no output argument is given, the p-value of the test is displayed.