Initial commit

dataassim/math/numrec/f77_sources/resid.for

@@ -0,0 +1,21 @@
+      SUBROUTINE resid(res,u,rhs,n)
+      INTEGER n
+      DOUBLE PRECISION res(n,n),rhs(n,n),u(n,n)
+      INTEGER i,j
+      DOUBLE PRECISION h,h2i
+      h=1.d0/(n-1)
+      h2i=1.d0/(h*h)
+      do 12 j=2,n-1
+        do 11 i=2,n-1
+          res(i,j)=-h2i*(u(i+1,j)+u(i-1,j)+u(i,j+1)+u(i,j-1)-4.d0*u(i,
+     *j))+rhs(i,j)
+11      continue
+12    continue
+      do 13 i=1,n
+        res(i,1)=0.d0
+        res(i,n)=0.d0
+        res(1,i)=0.d0
+        res(n,i)=0.d0
+13    continue
+      return
+      END