d9/da4/r9lgic_8f_source.html

 *DECK R9LGIC

       FUNCTION r9lgic (A, X, ALX)

 C***BEGIN PROLOGUE  R9LGIC

 C***SUBSIDIARY

 C***PURPOSE  Compute the log complementary incomplete Gamma function

 C            for large X and for A .LE. X.

 C***LIBRARY   SLATEC (FNLIB)

 C***CATEGORY  C7E

 C***TYPE      SINGLE PRECISION (R9LGIC-S, D9LGIC-D)

 C***KEYWORDS  COMPLEMENTARY INCOMPLETE GAMMA FUNCTION, FNLIB, LARGE X,

 C             LOGARITHM, SPECIAL FUNCTIONS

 C***AUTHOR  Fullerton, W., (LANL)

 C***DESCRIPTION

 C

 C Compute the log complementary incomplete gamma function for large X

 C and for A .LE. X.

 C

 C***REFERENCES  (NONE)

 C***ROUTINES CALLED  R1MACH, XERMSG

 C***REVISION HISTORY  (YYMMDD)

 C   770701  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   900720  Routine changed from user-callable to subsidiary.  (WRB)

 C***END PROLOGUE  R9LGIC

       SAVE eps

       DATA eps / 0.0 /

 C***FIRST EXECUTABLE STATEMENT  R9LGIC

       IF (eps.EQ.0.0) eps = 0.5*r1mach(3)

 C

       xpa = x + 1.0 - a

       xma = x - 1.0 - a

 C

       r = 0.0

       p = 1.0

       s = p

       DO 10 k=1,200

         fk = k

         t = fk*(a-fk)*(1.0+r)

         r = -t/((xma+2.0*fk)*(xpa+2.0*fk)+t)

         p = r*p

         s = s + p

         IF (abs(p).LT.eps*s) go to 20

  10   CONTINUE

       CALL xermsg('SLATEC', 'R9LGIC',

      +   'NO CONVERGENCE IN 200 TERMS OF CONTINUED FRACTION', 1, 2)

 C

  20   r9lgic = a*alx - x + log(s/xpa)

 C

       RETURN

       END

log
OCTAVE_EXPORT octave_value_list or N dimensional array whose elements are all equal to the base of natural logarithms The constant ex $e satisfies the equation log(e)

to
may be zero for pure relative error test tem the relative tolerance must be greater than or equal to
Definition: Quad-opts.cc:233

xermsg
subroutine xermsg(LIBRAR, SUBROU, MESSG, NERR, LEVEL)
Definition: xermsg.f:2

r9lgic
function r9lgic(A, X, ALX)
Definition: r9lgic.f:2

abs
OCTAVE_EXPORT octave_value_list return the value of the option it must match the dimension of the state and the relative tolerance must also be a vector of the same length tem it must match the dimension of the state and the absolute tolerance must also be a vector of the same length The local error test applied at each integration step is xample roup abs(local error in x(i))<