55 lines
1.2 KiB
FortranFixed
55 lines
1.2 KiB
FortranFixed
INTEGER FUNCTION IZAMAX(N,ZX,INCX)
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* .. Scalar Arguments ..
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INTEGER INCX,N
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* ..
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* .. Array Arguments ..
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DOUBLE COMPLEX ZX(*)
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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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* finds the index of element having max. absolute value.
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* jack dongarra, 1/15/85.
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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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DOUBLE PRECISION SMAX
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INTEGER I,IX
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* ..
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* .. External Functions ..
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DOUBLE PRECISION DCABS1
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EXTERNAL DCABS1
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* ..
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IZAMAX = 0
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IF (N.LT.1 .OR. INCX.LE.0) RETURN
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IZAMAX = 1
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IF (N.EQ.1) 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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IX = 1
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SMAX = DCABS1(ZX(1))
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IX = IX + INCX
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DO 10 I = 2,N
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IF (DCABS1(ZX(IX)).LE.SMAX) GO TO 5
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IZAMAX = I
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SMAX = DCABS1(ZX(IX))
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5 IX = IX + INCX
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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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20 SMAX = DCABS1(ZX(1))
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DO 30 I = 2,N
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IF (DCABS1(ZX(I)).LE.SMAX) GO TO 30
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IZAMAX = I
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SMAX = DCABS1(ZX(I))
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30 CONTINUE
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RETURN
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END
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