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, SAFEMN
Arguments
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
NoneExample
Program Text
NoneProgram Data
NoneProgram Results
None