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96 lines
1.8 KiB
96 lines
1.8 KiB
#include "clapack.h" |
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doublereal sdot_(integer *n, real *sx, integer *incx, real *sy, integer *incy) |
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{ |
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/* System generated locals */ |
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integer i__1; |
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real ret_val; |
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/* Local variables */ |
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integer i__, m, ix, iy, mp1; |
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real stemp; |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* forms the dot product of two vectors. */ |
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/* uses unrolled loops for increments equal to one. */ |
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/* jack dongarra, linpack, 3/11/78. */ |
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/* modified 12/3/93, array(1) declarations changed to array(*) */ |
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/* .. Local Scalars .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* Parameter adjustments */ |
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--sy; |
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--sx; |
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/* Function Body */ |
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stemp = 0.f; |
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ret_val = 0.f; |
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if (*n <= 0) { |
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return ret_val; |
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} |
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if (*incx == 1 && *incy == 1) { |
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goto L20; |
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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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ix = 1; |
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iy = 1; |
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if (*incx < 0) { |
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ix = (-(*n) + 1) * *incx + 1; |
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} |
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if (*incy < 0) { |
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iy = (-(*n) + 1) * *incy + 1; |
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} |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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stemp += sx[ix] * sy[iy]; |
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ix += *incx; |
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iy += *incy; |
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/* L10: */ |
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} |
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ret_val = stemp; |
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return ret_val; |
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/* code for both increments equal to 1 */ |
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/* clean-up loop */ |
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L20: |
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m = *n % 5; |
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if (m == 0) { |
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goto L40; |
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} |
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i__1 = m; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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stemp += sx[i__] * sy[i__]; |
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/* L30: */ |
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} |
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if (*n < 5) { |
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goto L60; |
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} |
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L40: |
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mp1 = m + 1; |
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i__1 = *n; |
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for (i__ = mp1; i__ <= i__1; i__ += 5) { |
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stemp = stemp + sx[i__] * sy[i__] + sx[i__ + 1] * sy[i__ + 1] + sx[ |
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i__ + 2] * sy[i__ + 2] + sx[i__ + 3] * sy[i__ + 3] + sx[i__ + |
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4] * sy[i__ + 4]; |
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/* L50: */ |
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} |
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L60: |
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ret_val = stemp; |
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return ret_val; |
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} /* sdot_ */
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