dd/d25/genchi_8f_source.html

       REAL FUNCTION genchi(df)

 C**********************************************************************

 C

 C     REAL FUNCTION GENCHI( DF )

 C                Generate random value of CHIsquare variable

 C

 C

 C                              Function

 C

 C

 C     Generates random deviate from the distribution of a chisquare

 C     with DF degrees of freedom random variable.

 C

 C

 C                              Arguments

 C

 C

 C     DF --> Degrees of freedom of the chisquare

 C            (Must be positive)

 C                         REAL DF

 C

 C

 C                              Method

 C

 C

 C     Uses relation between chisquare and gamma.

 C

 C**********************************************************************

 C     .. Scalar Arguments ..

       REAL df

 C     ..

 C     .. External Functions ..

 C      REAL gengam

 C      EXTERNAL gengam

       REAL sgamma

       EXTERNAL sgamma

 C     ..

 C     .. Executable Statements ..

       IF (.NOT. (df.LE.0.0)) go to 10

       WRITE (*,*) 'DF <= 0 in GENCHI - ABORT'

       WRITE (*,*) 'Value of DF: ',df

       CALL xstopx('DF <= 0 in GENCHI - ABORT')


 C     JJV changed this to call sgamma directly

 C   10 genchi = 2.0*gengam(1.0,df/2.0)

  10   genchi = 2.0*sgamma(df/2.0)

       RETURN


       END

genchi
real function genchi(df)
Definition: genchi.f:1