F-distribution CDF
p = distfun_fcdf(x,v1,v2) p = distfun_fcdf(x,v1,v2,lowertail)
a matrix of doubles. x is real and x>=0.
a matrix of doubles, numerator degrees of freedom, v1>0 (can be non integer).
a matrix of doubles, denominator degrees of freedom, v2>0 (can be non integer).
a 1-by-1 matrix of booleans, the tail (default lowertail=%t). If lowertail is true (the default), then considers P(X<=x) otherwise P(X>x).
a matrix of doubles, the probability.
Computes the cumulative distribution function of the f distribution function.
Any scalar input argument is expanded to a matrix of doubles of the same size as the other input arguments.
// Test with x, v1, v2 scalar computed = distfun_fcdf(2,1,6) expected = 7.929687500000000000D-01 // Test with x expanded, v1 and v2 scalar computed = distfun_fcdf([2 5],1,6) expected = [ 7.929687500000000000D-01 9.332931980379590708D-01 ]' // Test with x,v1,v2 expanded computed = distfun_fcdf(2:6,1:5,6:10) expected = [ 7.929687500000000000D-01 8.854377836609319541D-01 9.481063231515756140D-01 9.787944634589056392D-01 9.919248908050191105D-01 ]' // Plot the function h=scf(); x = linspace(0,5,1000); p1 = distfun_fcdf(x,1,1); p2 = distfun_fcdf(x,2,1); p3 = distfun_fcdf(x,5,2); p4 = distfun_fcdf(x,100,1); p5 = distfun_fcdf(x,100,100); plot(x,p1,"r") plot(x,p2,"g") plot(x,p3,"b") plot(x,p4,"y") plot(x,p5,"k") legend([ "v1=1, v2=1" "v1=2, v2=1"; "v1=5, v2=2" "v1=100, v2=1" "v1=100, v2=100" ]); xtitle("F CDF","x","$P(X\leq x)$"); | ![]() | ![]() |
http://en.wikipedia.org/wiki/F-distribution