kjb_scaled_bessel_I1 - Computes a ratio: bessel I1(x) over exp(x)
Example compile flags (system dependent):
-DLINUX_X86_64 -DLINUX_X86_64_OPTERON -DGNU_COMPILER
-lKJB -lfftw3 -lgsl -lgslcblas -ljpeg -lSVM -lstdc++ -lpthread -lSLATEC -lg2c -lacml -lacml_mv -lblas -lg2c -lncursesw
Pointer to where the result should be stored
Value at which to evaluate erf
If possible, computes a product: the modified Bessel function, order 1
(usually denoted by something like I_1(x) times exp(-x)).
The scaling factor is a practical necessity when x is large, since the
function grows quickly, yet we sometimes need to compute ratios of these
This routine is a thin wrapper to GSL code that computes this special
function. If the GSL library is not available, this routine fails with a
return value of ERROR. Otherwise, the value is returned in the location
pointed to by pointer P_ptr, which must not equal null. The argument to
the function is stored in x.
If successful, the value is written to *P_ptr and this function returns
NO_ERROR. If the routine fails -- caused by the library being unavailable
during linking -- an error message is set and the return value is ERROR.
This software is not adequatedly tested. It is recomended that
results are checked independantly where appropriate.