If you have the Statistics Toolbox, the tcdf function will do what you want.
If not, the t-probability calculation is a one-line anonymous function:
tdist2T = @(t,v) (1-betainc(v/(v+t^2),v/2,0.5)); % 2-tailed t-distribution
tdist1T = @(t,v) 1-(1-tdist2T(t,v))/2; % 1-tailed t-distribution
where ‘t’ is the t-statistic and ‘v’ are the degrees-of-freedom. (Note that ‘tdist1T’ calls ‘tdist2T’.)
