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