root / src / blas / zdotu.f @ 4
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DOUBLE COMPLEX FUNCTION ZDOTU(N,ZX,INCX,ZY,INCY) |
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* .. Scalar Arguments .. |
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INTEGER INCX,INCY,N |
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* .. |
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* .. Array Arguments .. |
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DOUBLE COMPLEX ZX(*),ZY(*) |
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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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* ZDOTU forms the dot product of two vectors. |
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* |
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* Further Details |
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* =============== |
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* |
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* jack dongarra, 3/11/78. |
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* modified 12/3/93, array(1) declarations changed to array(*) |
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* |
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* .. Local Scalars .. |
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DOUBLE COMPLEX ZTEMP |
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INTEGER I,IX,IY |
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* .. |
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ZTEMP = (0.0d0,0.0d0) |
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ZDOTU = (0.0d0,0.0d0) |
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IF (N.LE.0) RETURN |
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IF (INCX.EQ.1 .AND. INCY.EQ.1) GO TO 20 |
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* |
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* code for unequal increments or equal increments |
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* not equal to 1 |
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* |
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IX = 1 |
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IY = 1 |
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IF (INCX.LT.0) IX = (-N+1)*INCX + 1 |
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IF (INCY.LT.0) IY = (-N+1)*INCY + 1 |
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DO 10 I = 1,N |
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ZTEMP = ZTEMP + ZX(IX)*ZY(IY) |
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IX = IX + INCX |
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IY = IY + INCY |
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10 CONTINUE |
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ZDOTU = ZTEMP |
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RETURN |
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* |
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* code for both increments equal to 1 |
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* |
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20 DO 30 I = 1,N |
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ZTEMP = ZTEMP + ZX(I)*ZY(I) |
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30 CONTINUE |
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ZDOTU = ZTEMP |
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RETURN |
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END |