FUNCTION gasdev(idum) INTEGER idum REAL gasdev CU USES ran1 INTEGER iset REAL fac,gset,rsq,v1,v2,ran1 SAVE iset,gset DATA iset/0/ if (iset.eq.0) then 1 v1=2.*ran1(idum)-1. v2=2.*ran1(idum)-1. rsq=v1**2+v2**2 if(rsq.ge.1..or.rsq.eq.0.)goto 1 fac=sqrt(-2.*log(rsq)/rsq) gset=v1*fac gasdev=v2*fac iset=1 else gasdev=gset iset=0 endif return END C (C) Copr. 1986-92 Numerical Recipes Software *(t9,12.