| 123456789101112131415161718192021222324252627282930313233343536373839 |
- *DECK PYTHAG
- REAL FUNCTION PYTHAG (A, B)
- C***BEGIN PROLOGUE PYTHAG
- C***SUBSIDIARY
- C***PURPOSE Compute the complex square root of a complex number without
- C destructive overflow or underflow.
- C***LIBRARY SLATEC
- C***TYPE SINGLE PRECISION (PYTHAG-S)
- C***AUTHOR (UNKNOWN)
- C***DESCRIPTION
- C
- C Finds sqrt(A**2+B**2) without overflow or destructive underflow
- C
- C***SEE ALSO EISDOC
- C***ROUTINES CALLED (NONE)
- C***REVISION HISTORY (YYMMDD)
- C 811101 DATE WRITTEN
- C 890531 Changed all specific intrinsics to generic. (WRB)
- C 891214 Prologue converted to Version 4.0 format. (BAB)
- C 900402 Added TYPE section. (WRB)
- C***END PROLOGUE PYTHAG
- REAL A,B
- C
- REAL P,Q,R,S,T
- C***FIRST EXECUTABLE STATEMENT PYTHAG
- P = MAX(ABS(A),ABS(B))
- Q = MIN(ABS(A),ABS(B))
- IF (Q .EQ. 0.0E0) GO TO 20
- 10 CONTINUE
- R = (Q/P)**2
- T = 4.0E0 + R
- IF (T .EQ. 4.0E0) GO TO 20
- S = R/T
- P = P + 2.0E0*P*S
- Q = Q*S
- GO TO 10
- 20 PYTHAG = P
- RETURN
- END
|
