mirror of
https://github.com/LCPQ/DEHam
synced 2024-12-22 20:34:28 +01:00
101 lines
8.1 KiB
FortranFixed
101 lines
8.1 KiB
FortranFixed
|
DOUBLE PRECISION FUNCTION DGAMMA(X)
|
||
|
|
INTEGER I,N
|
||
|
|
LOGICAL PARITY
|
||
|
|
DIMENSION C(7),P(8),Q(8)
|
||
|
|
DOUBLE PRECISION &
|
||
|
|
C,CONV,EPS,FACT,HALF,ONE,P,PI,Q,RES,SQRTPI,SUM,TWELVE, &
|
||
|
|
TWO,X,XBIG,XDEN,XINF,XMININ,XNUM,Y,Y1,YSQ,Z,ZERO ! gamma.irp.f: 95
|
||
|
|
DATA ONE,HALF,TWELVE,TWO,ZERO/1.0D0,0.5D0,12.0D0,2.0D0,0.0D0/,&
|
||
|
|
SQRTPI/0.9189385332046727417803297D0/, &
|
||
|
|
PI/3.1415926535897932384626434D0/ ! gamma.irp.f: 105
|
||
|
|
DATA XBIG,XMININ,EPS/171.624D0,2.23D-308,2.22D-16/,&
|
||
|
|
XINF/1.79D308/ ! gamma.irp.f: 113
|
||
|
|
DATA P/-1.71618513886549492533811D+0,2.47656508055759199108314D+1,&
|
||
|
|
-3.79804256470945635097577D+2,6.29331155312818442661052D+2, &
|
||
|
|
8.66966202790413211295064D+2,-3.14512729688483675254357D+4, &
|
||
|
|
-3.61444134186911729807069D+4,6.64561438202405440627855D+4/ ! gamma.irp.f: 127
|
||
|
|
DATA Q/-3.08402300119738975254353D+1,3.15350626979604161529144D+2,&
|
||
|
|
-1.01515636749021914166146D+3,-3.10777167157231109440444D+3, &
|
||
|
|
2.25381184209801510330112D+4,4.75584627752788110767815D+3, &
|
||
|
|
-1.34659959864969306392456D+5,-1.15132259675553483497211D+5/ ! gamma.irp.f: 131
|
||
|
|
DATA C/-1.910444077728D-03,8.4171387781295D-04,&
|
||
|
|
-5.952379913043012D-04,7.93650793500350248D-04, &
|
||
|
|
-2.777777777777681622553D-03,8.333333333333333331554247D-02, &
|
||
|
|
5.7083835261D-03/ ! gamma.irp.f: 142
|
||
|
|
I = DBLE(I) ! gamma.irp.f: 150
|
||
|
|
PARITY = .FALSE. ! gamma.irp.f: 151
|
||
|
|
FACT = ONE ! gamma.irp.f: 152
|
||
|
|
N = 0 ! gamma.irp.f: 153
|
||
|
|
Y = X ! gamma.irp.f: 154
|
||
|
|
IF (Y .LE. ZERO) THEN ! gamma.irp.f: 155
|
||
|
|
Y = -X ! gamma.irp.f: 159
|
||
|
|
Y1 = AINT(Y) ! gamma.irp.f: 160
|
||
|
|
RES = Y - Y1 ! gamma.irp.f: 161
|
||
|
|
IF (RES .NE. ZERO) THEN ! gamma.irp.f: 162
|
||
|
|
IF (Y1 .NE. AINT(Y1*HALF)*TWO) then ! gamma.irp.f: 163
|
||
|
|
PARITY = .TRUE. ! gamma.irp.f: 163
|
||
|
|
endif ! gamma.irp.f: 163
|
||
|
|
FACT = -PI / SIN(PI*RES) ! gamma.irp.f: 164
|
||
|
|
Y = Y + ONE ! gamma.irp.f: 165
|
||
|
|
ELSE ! gamma.irp.f: 166
|
||
|
|
RES = XINF ! gamma.irp.f: 167
|
||
|
|
GO TO 900 ! gamma.irp.f: 168
|
||
|
|
END IF ! gamma.irp.f: 169
|
||
|
|
END IF ! gamma.irp.f: 170
|
||
|
|
IF (Y .LT. EPS) THEN ! gamma.irp.f: 174
|
||
|
|
IF (Y .GE. XMININ) THEN ! gamma.irp.f: 178
|
||
|
|
RES = ONE / Y ! gamma.irp.f: 179
|
||
|
|
ELSE ! gamma.irp.f: 180
|
||
|
|
RES = XINF ! gamma.irp.f: 181
|
||
|
|
GO TO 900 ! gamma.irp.f: 182
|
||
|
|
END IF ! gamma.irp.f: 183
|
||
|
|
ELSE IF (Y .LT. TWELVE) THEN ! gamma.irp.f: 184
|
||
|
|
Y1 = Y ! gamma.irp.f: 185
|
||
|
|
IF (Y .LT. ONE) THEN ! gamma.irp.f: 186
|
||
|
|
Z = Y ! gamma.irp.f: 190
|
||
|
|
Y = Y + ONE ! gamma.irp.f: 191
|
||
|
|
ELSE ! gamma.irp.f: 192
|
||
|
|
N = INT(Y) - 1 ! gamma.irp.f: 196
|
||
|
|
Y = Y - N ! gamma.irp.f: 197
|
||
|
|
Z = Y - ONE ! gamma.irp.f: 198
|
||
|
|
END IF ! gamma.irp.f: 199
|
||
|
|
XNUM = ZERO ! gamma.irp.f: 203
|
||
|
|
XDEN = ONE ! gamma.irp.f: 204
|
||
|
|
DO I = 1, 8 ! gamma.irp.f: 205
|
||
|
|
XNUM = (XNUM + P(I)) * Z ! gamma.irp.f: 206
|
||
|
|
XDEN = XDEN * Z + Q(I) ! gamma.irp.f: 207
|
||
|
|
enddo ! gamma.irp.f: 208
|
||
|
|
RES = XNUM / XDEN + ONE ! gamma.irp.f: 209
|
||
|
|
IF (Y1 .LT. Y) THEN ! gamma.irp.f: 210
|
||
|
|
RES = RES / Y1 ! gamma.irp.f: 214
|
||
|
|
ELSE IF (Y1 .GT. Y) THEN ! gamma.irp.f: 215
|
||
|
|
DO I = 1, N ! gamma.irp.f: 219
|
||
|
|
RES = RES * Y ! gamma.irp.f: 220
|
||
|
|
Y = Y + ONE ! gamma.irp.f: 221
|
||
|
|
enddo ! gamma.irp.f: 222
|
||
|
|
END IF ! gamma.irp.f: 223
|
||
|
|
ELSE ! gamma.irp.f: 224
|
||
|
|
IF (Y .LE. XBIG) THEN ! gamma.irp.f: 228
|
||
|
|
YSQ = Y * Y ! gamma.irp.f: 229
|
||
|
|
SUM = C(7) ! gamma.irp.f: 230
|
||
|
|
DO I = 1, 6 ! gamma.irp.f: 231
|
||
|
|
SUM = SUM / YSQ + C(I) ! gamma.irp.f: 232
|
||
|
|
enddo ! gamma.irp.f: 233
|
||
|
|
SUM = SUM/Y - Y + SQRTPI ! gamma.irp.f: 234
|
||
|
|
SUM = SUM + (Y-HALF)*LOG(Y) ! gamma.irp.f: 235
|
||
|
|
RES = EXP(SUM) ! gamma.irp.f: 236
|
||
|
|
ELSE ! gamma.irp.f: 237
|
||
|
|
RES = XINF ! gamma.irp.f: 238
|
||
|
|
GO TO 900 ! gamma.irp.f: 239
|
||
|
|
END IF ! gamma.irp.f: 240
|
||
|
|
END IF ! gamma.irp.f: 241
|
||
|
|
IF (PARITY) then ! gamma.irp.f: 245
|
||
|
|
RES = -RES ! gamma.irp.f: 245
|
||
|
|
endif ! gamma.irp.f: 245
|
||
|
|
IF (FACT .NE. ONE) then ! gamma.irp.f: 246
|
||
|
|
RES = FACT / RES ! gamma.irp.f: 246
|
||
|
|
endif ! gamma.irp.f: 246
|
||
|
|
900 DGAMMA = RES ! gamma.irp.f: 248
|
||
|
|
RETURN ! gamma.irp.f: 249
|
||
|
|
end ! gamma.irp.f: 251
|