Initial commit

dataassim/math/numrec/f77_sources/gasdev.for

@@ -0,0 +1,23 @@
+      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