1 DOUBLE PRECISION FUNCTION genchi(df) 2C********************************************************************** 3C 4C DOUBLE PRECISION FUNCTION GENCHI( DF ) 5C Generate random value of CHIsquare variable 6C 7C 8C Function 9C 10C 11C Generates random deviate from the distribution of a chisquare 12C with DF degrees of freedom random variable. 13C 14C 15C Arguments 16C 17C 18C DF --> Degrees of freedom of the chisquare 19C (Must be positive) 20C DOUBLE PRECISION DF 21C 22C 23C Method 24C 25C 26C Uses relation between chisquare and gamma. 27C 28C********************************************************************** 29C .. Scalar Arguments .. 30 DOUBLE PRECISION df 31C .. 32C .. External Functions .. 33C DOUBLE PRECISION gengam 34C EXTERNAL gengam 35 DOUBLE PRECISION sgamma 36 EXTERNAL sgamma 37C .. 38C .. Executable Statements .. 39C JJV changed this to call sgamma directly 40C 10 genchi = 2.0*gengam(1.0,df/2.0) 41 10 genchi = 2.0*sgamma(df/2.0) 42 RETURN 43 44 END 45