Initial commit

dataassim/math/numrec/f77_sources/ran1.for

@@ -0,0 +1,27 @@
+      FUNCTION ran1(idum)
+      INTEGER idum,IA,IM,IQ,IR,NTAB,NDIV
+      REAL ran1,AM,EPS,RNMX
+      PARAMETER (IA=16807,IM=2147483647,AM=1./IM,IQ=127773,IR=2836,
+     *NTAB=32,NDIV=1+(IM-1)/NTAB,EPS=1.2e-7,RNMX=1.-EPS)
+      INTEGER j,k,iv(NTAB),iy
+      SAVE iv,iy
+      DATA iv /NTAB*0/, iy /0/
+      if (idum.le.0.or.iy.eq.0) then
+        idum=max(-idum,1)
+        do 11 j=NTAB+8,1,-1
+          k=idum/IQ
+          idum=IA*(idum-k*IQ)-IR*k
+          if (idum.lt.0) idum=idum+IM
+          if (j.le.NTAB) iv(j)=idum
+11      continue
+        iy=iv(1)
+      endif
+      k=idum/IQ
+      idum=IA*(idum-k*IQ)-IR*k
+      if (idum.lt.0) idum=idum+IM
+      j=1+iy/NDIV
+      iy=iv(j)
+      iv(j)=idum
+      ran1=min(AM*iy,RNMX)
+      return
+      END