Initial commit

dataassim/math/numrec/f77_sources/relax2.for

@@ -0,0 +1,23 @@
+      SUBROUTINE relax2(u,rhs,n)
+      INTEGER n
+      DOUBLE PRECISION rhs(n,n),u(n,n)
+      INTEGER i,ipass,isw,j,jsw
+      DOUBLE PRECISION foh2,h,h2i,res
+      h=1.d0/(n-1)
+      h2i=1.d0/(h*h)
+      foh2=-4.d0*h2i
+      jsw=1
+      do 13 ipass=1,2
+        isw=jsw
+        do 12 j=2,n-1
+          do 11 i=isw+1,n-1,2
+            res=h2i*(u(i+1,j)+u(i-1,j)+u(i,j+1)+u(i,j-1)-4.d0*u(i,j))+
+     *u(i,j)**2-rhs(i,j)
+            u(i,j)=u(i,j)-res/(foh2+2.d0*u(i,j))
+11        continue
+          isw=3-isw
+12      continue
+        jsw=3-jsw
+13    continue
+      return
+      END