git push -u origin main

synspec/extracted/tridag.f

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+      SUBROUTINE TRIDAG(A,B,C,R,U,N)
+C     ==============================
+C
+C     Solve tridiagonal system of equations
+C      from Numerical Recipes (standard Gaussian elimination)
+C
+      INCLUDE 'PARAMS.FOR'
+      INCLUDE 'WINCOM.FOR'
+      DIMENSION A(N),B(N),C(N),R(N),U(N)
+      DIMENSION GTRID(MKU)
+C
+      BTRID=B(1)
+      U(1)=R(1)/BTRID
+      DO J=2,N
+        GTRID(J)=C(J-1)/BTRID
+        BTRID=B(J)-A(J)*GTRID(J)
+        U(J)=(R(J)-A(J)*U(J-1))/BTRID
+      ENDDO
+      DO J=N-1,1,-1
+        U(J)=U(J)-GTRID(J+1)*U(J+1)
+      ENDDO
+C
+      RETURN
+      END