53 lines
1.1 KiB
C
53 lines
1.1 KiB
C
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#include "hypre_lapack.h"
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#include "f2c.h"
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doublereal dlapy2_(doublereal *x, doublereal *y)
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{
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/* -- LAPACK auxiliary routine (version 3.0) --
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Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
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Courant Institute, Argonne National Lab, and Rice University
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October 31, 1992
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Purpose
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=======
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DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
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overflow.
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Arguments
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=========
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X (input) DOUBLE PRECISION
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Y (input) DOUBLE PRECISION
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X and Y specify the values x and y.
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===================================================================== */
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/* System generated locals */
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doublereal ret_val, d__1;
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/* Builtin functions */
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double sqrt(doublereal);
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/* Local variables */
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static doublereal xabs, yabs, w, z__;
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xabs = abs(*x);
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yabs = abs(*y);
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w = max(xabs,yabs);
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z__ = min(xabs,yabs);
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if (z__ == 0.) {
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ret_val = w;
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} else {
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/* Computing 2nd power */
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d__1 = z__ / w;
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ret_val = w * sqrt(d__1 * d__1 + 1.);
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}
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return ret_val;
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/* End of DLAPY2 */
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} /* dlapy2_ */
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