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- *DECK CCOT
- COMPLEX FUNCTION CCOT (Z)
- C***BEGIN PROLOGUE CCOT
- C***PURPOSE Compute the cotangent.
- C***LIBRARY SLATEC (FNLIB)
- C***CATEGORY C4A
- C***TYPE COMPLEX (COT-S, DCOT-D, CCOT-C)
- C***KEYWORDS COTANGENT, ELEMENTARY FUNCTIONS, FNLIB, TRIGONOMETRIC
- C***AUTHOR Fullerton, W., (LANL)
- C***DESCRIPTION
- C
- C CCOT(Z) calculates the complex trigonometric cotangent of Z.
- C
- C***REFERENCES (NONE)
- C***ROUTINES CALLED R1MACH, XERCLR, XERMSG
- C***REVISION HISTORY (YYMMDD)
- C 770401 DATE WRITTEN
- C 890531 Changed all specific intrinsics to generic. (WRB)
- C 890531 REVISION DATE from Version 3.2
- C 891214 Prologue converted to Version 4.0 format. (BAB)
- C 900315 CALLs to XERROR changed to CALLs to XERMSG. (THJ)
- C 900326 Removed duplicate information from DESCRIPTION section.
- C (WRB)
- C***END PROLOGUE CCOT
- COMPLEX Z
- SAVE SQEPS
- DATA SQEPS /0./
- C***FIRST EXECUTABLE STATEMENT CCOT
- IF (SQEPS.EQ.0.) SQEPS = SQRT (R1MACH(4))
- C
- X2 = 2.0*REAL(Z)
- Y2 = 2.0*AIMAG(Z)
- C
- SN2X = SIN (X2)
- CALL XERCLR
- C
- DEN = COSH(Y2) - COS(X2)
- IF (DEN .EQ. 0.) CALL XERMSG ('SLATEC', 'CCOT',
- + 'COT IS SINGULAR FOR INPUT Z (X IS 0 OR PI AND Y IS 0)', 2, 2)
- C
- IF (ABS(DEN).GT.MAX(ABS(X2),1.)*SQEPS) GO TO 10
- CALL XERCLR
- CALL XERMSG ('SLATEC', 'CCOT',
- + 'ANSWER LT HALF PRECISION, ABS(X) TOO BIG OR X TOO NEAR ' //
- + '0 OR PI', 1, 1)
- C
- 10 CCOT = CMPLX (SN2X/DEN, -SINH(Y2)/DEN)
- C
- RETURN
- END
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