The inverse of the Marcum-Q function

can any one help me on my problem which is how to get the inverse of marcum Q function

[Muhammad Adil]

working on same problem bro ..... read this "Approximate Inversion of Marcum Q function" by Carl W helstorm, maybe it will help

Answer 1

[Wayne King]

Do you have the Communications System Toolbox?

See the help for qfuncinv.m

If you don't have the CST, you can use erfcinv.m

    x = [0.5000    0.1587    0.0228];
    y = sqrt(2) * erfcinv(2*x);

[mutah]

my dear i mean the inverse of this equation :

       Q_m(a,b) = 1/a^(m-1) * integral from b to inf of
                  [x^m * exp(-(x^2+a^2)/2) * I_(m-1)(ax)] dx,

    where I_(m-1)() is the modified Bessel function of the first kind, of
    order m-1.