Annotation of rpl/lapack/blas/dscal.f, revision 1.7
1.1 bertrand 1: SUBROUTINE DSCAL(N,DA,DX,INCX)
2: * .. Scalar Arguments ..
3: DOUBLE PRECISION DA
4: INTEGER INCX,N
5: * ..
6: * .. Array Arguments ..
7: DOUBLE PRECISION DX(*)
8: * ..
9: *
10: * Purpose
11: * =======
12: *
13: * DSCAL scales a vector by a constant.
14: * uses unrolled loops for increment equal to one.
15: *
16: * Further Details
17: * ===============
18: *
19: * jack dongarra, linpack, 3/11/78.
20: * modified 3/93 to return if incx .le. 0.
21: * modified 12/3/93, array(1) declarations changed to array(*)
22: *
23: * =====================================================================
24: *
25: * .. Local Scalars ..
26: INTEGER I,M,MP1,NINCX
27: * ..
28: * .. Intrinsic Functions ..
29: INTRINSIC MOD
30: * ..
31: IF (N.LE.0 .OR. INCX.LE.0) RETURN
1.7 ! bertrand 32: IF (INCX.EQ.1) THEN
1.1 bertrand 33: *
1.7 ! bertrand 34: * code for increment equal to 1
1.1 bertrand 35: *
36: *
1.7 ! bertrand 37: * clean-up loop
1.1 bertrand 38: *
1.7 ! bertrand 39: M = MOD(N,5)
! 40: IF (M.NE.0) THEN
! 41: DO I = 1,M
! 42: DX(I) = DA*DX(I)
! 43: END DO
! 44: IF (N.LT.5) RETURN
! 45: END IF
! 46: MP1 = M + 1
! 47: DO I = MP1,N,5
! 48: DX(I) = DA*DX(I)
! 49: DX(I+1) = DA*DX(I+1)
! 50: DX(I+2) = DA*DX(I+2)
! 51: DX(I+3) = DA*DX(I+3)
! 52: DX(I+4) = DA*DX(I+4)
! 53: END DO
! 54: ELSE
1.1 bertrand 55: *
1.7 ! bertrand 56: * code for increment not equal to 1
1.1 bertrand 57: *
1.7 ! bertrand 58: NINCX = N*INCX
! 59: DO I = 1,NINCX,INCX
! 60: DX(I) = DA*DX(I)
! 61: END DO
! 62: END IF
1.1 bertrand 63: RETURN
64: END
CVSweb interface <joel.bertrand@systella.fr>