| 12345678910111213141516171819202122232425262728293031323334353637 |
- *DECK DCOSDG
- DOUBLE PRECISION FUNCTION DCOSDG (X)
- C***BEGIN PROLOGUE DCOSDG
- C***PURPOSE Compute the cosine of an argument in degrees.
- C***LIBRARY SLATEC (FNLIB)
- C***CATEGORY C4A
- C***TYPE DOUBLE PRECISION (COSDG-S, DCOSDG-D)
- C***KEYWORDS COSINE, DEGREES, ELEMENTARY FUNCTIONS, FNLIB,
- C TRIGONOMETRIC
- C***AUTHOR Fullerton, W., (LANL)
- C***DESCRIPTION
- C
- C DCOSDG(X) calculates the double precision trigonometric cosine
- C for double precision argument X in units of degrees.
- C
- C***REFERENCES (NONE)
- C***ROUTINES CALLED (NONE)
- C***REVISION HISTORY (YYMMDD)
- C 770601 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***END PROLOGUE DCOSDG
- DOUBLE PRECISION X, RADDEG
- SAVE RADDEG
- DATA RADDEG / 0.0174532925 1994329576 9236907684 886 D0 /
- C***FIRST EXECUTABLE STATEMENT DCOSDG
- DCOSDG = COS (RADDEG*X)
- C
- IF (MOD(X,90.D0).NE.0.D0) RETURN
- N = ABS(X)/90.D0 + 0.5D0
- N = MOD (N, 2)
- IF (N.EQ.0) DCOSDG = SIGN (1.0D0, DCOSDG)
- IF (N.EQ.1) DCOSDG = 0.0D0
- C
- RETURN
- END
|
