Purpose
To compute an approximate symmetric chordal metric for two complex numbers A1 and A2, with Aj = ARj + i*AIj, j = 1, 2.Specification
SUBROUTINE MA01DD( AR1, AI1, AR2, AI2, EPS, SAFEMN, D ) C .. Scalar Arguments .. DOUBLE PRECISION AI1, AI2, AR1, AR2, D, EPS, SAFEMNArguments
Input/Output Parameters
AR1 (input) DOUBLE PRECISION AI1 (input) DOUBLE PRECISION These scalars define the real and imaginary parts of the number A1. AR2 (input) DOUBLE PRECISION AI2 (input) DOUBLE PRECISION These scalars define the real and imaginary parts of the number A2. EPS (input) DOUBLE PRECISION The relative machine precision. See the LAPACK Library routine DLAMCH. SAFEMN (input) DOUBLE PRECISION The "safe minimum", such that its reciprocal does not overflow. See the LAPACK Library routine DLAMCH. D (output) DOUBLE PRECISION The approximate symmetric chordal metric D. D >= 0.Method
The approximate symmetric chordal metric is evaluated using the formula D = MIN( | A1 - A2 |, |1/A1 - 1/A2| ). The chordal metric is finite even if A1 and A2 are both infinite, or if one of them is infinite and the other is finite, nonzero.Further Comments
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