i want to compute a cdf for t distribution

i want to compute a cdf for t distribution from a to b , i wrote this code but it didn't run

for i=1:50

fa(i)=cdf('t', 'mu' =-2, 'sigma'= 4 , 'nu'= 6 , astar(i))

fb(i)=cdf('t', 'mu' =-2, 'sigma'= 4 , 'nu'= 6, bstar(i))

end

astar and bstar are points of the integral

sorry for a weak my language

Answer 1

[Star Strider]

You are not calling cdf correctly. Also the functions are vectorised, so you do not need the loops.

Try this:

fa = cdf('T', nu, astar);
fb = cdf('T', nu, bstar);

It is probably best to use the tcdf (link) function instead, since cdf appears to be deprecated in a future release of MATLAB.

[elham kreem]

thanks for you , your answer for stander dist. and i apply it as : fa = cdf('T', 'nu', 6, astar) the result is : fa =

    1.0000    1.0000

 but if i want  cdf for non stander distribution for t, I apply this code 
 fa=cdf('T', 'mu' ,-2, 'sigma', 4 , 'nu', 6 , astar)
but the result is :
fa =

   NaN   NaN

[Star Strider]

My pleasure.

In the t-distribution, ‘nu’ is calculated as described in Compute Student's t cdf (link). You use the mean (‘mu’), standard deviation (‘sigma’) and number of observations (‘n’) to calculate it. There is only one parameter.

If you use my code, you get the correct result:

astar = linspace(1E-5, 2, 5);
nu = 6;
fa = cdf('T', nu, astar)

I again urge you to use the tcdf function (that I linked to in my Answer), instead of cdf.