git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@7435 f3b2605a-c512-4ea7-a41b-209d697bcdaa

lib/linalg/dscal.f

@@ -0,0 +1,62 @@
+      SUBROUTINE DSCAL(N,DA,DX,INCX)
+*     .. Scalar Arguments ..
+      DOUBLE PRECISION DA
+      INTEGER INCX,N
+*     ..
+*     .. Array Arguments ..
+      DOUBLE PRECISION DX(*)
+*     ..
+*
+*  Purpose
+*  =======
+*
+*     DSCAL scales a vector by a constant.
+*     uses unrolled loops for increment equal to one.
+*
+*  Further Details
+*  ===============
+*
+*     jack dongarra, linpack, 3/11/78.
+*     modified 3/93 to return if incx .le. 0.
+*     modified 12/3/93, array(1) declarations changed to array(*)
+*
+*  =====================================================================
+*
+*     .. Local Scalars ..
+      INTEGER I,M,MP1,NINCX
+*     ..
+*     .. Intrinsic Functions ..
+      INTRINSIC MOD
+*     ..
+      IF (N.LE.0 .OR. INCX.LE.0) RETURN
+      IF (INCX.EQ.1) GO TO 20
+*
+*        code for increment not equal to 1
+*
+      NINCX = N*INCX
+      DO 10 I = 1,NINCX,INCX
+          DX(I) = DA*DX(I)
+   10 CONTINUE
+      RETURN
+*
+*        code for increment equal to 1
+*
+*
+*        clean-up loop
+*
+   20 M = MOD(N,5)
+      IF (M.EQ.0) GO TO 40
+      DO 30 I = 1,M
+          DX(I) = DA*DX(I)
+   30 CONTINUE
+      IF (N.LT.5) RETURN
+   40 MP1 = M + 1
+      DO 50 I = MP1,N,5
+          DX(I) = DA*DX(I)
+          DX(I+1) = DA*DX(I+1)
+          DX(I+2) = DA*DX(I+2)
+          DX(I+3) = DA*DX(I+3)
+          DX(I+4) = DA*DX(I+4)
+   50 CONTINUE
+      RETURN
+      END