specfunc-pow-int.texi

开放gsl矩阵运算

@cindex power function
@cindex integer powers

The following functions are equivalent to the function @code{gsl_pow_int}
(@pxref{Small integer powers}) with an error estimate.  These functions are
declared in the header file @file{gsl_sf_pow_int.h}.

@deftypefun double gsl_sf_pow_int (double @var{x}, int @var{n})
@deftypefunx int gsl_sf_pow_int_e (double @var{x}, int @var{n}, gsl_sf_result * @var{result}) 
These routines compute the power @math{x^n} for integer @var{n}.  The
power is computed using the minimum number of multiplications. For
example, @math{x^8} is computed as @math{((x^2)^2)^2}, requiring only 3
multiplications.  For reasons of efficiency, these functions do not
check for overflow or underflow conditions.
@end deftypefun

@example
#include <gsl/gsl_sf_pow_int.h>
/* compute 3.0**12 */
double y = gsl_sf_pow_int(3.0, 12); 
@end example