diff options
Diffstat (limited to 'test/math/elog.c')
-rw-r--r-- | test/math/elog.c | 92 |
1 files changed, 0 insertions, 92 deletions
diff --git a/test/math/elog.c b/test/math/elog.c deleted file mode 100644 index bc517b197..000000000 --- a/test/math/elog.c +++ /dev/null @@ -1,92 +0,0 @@ -/* xlog.c */ -/* natural logarithm */ -/* by Stephen L. Moshier. */ - -#include "mconf.h" -#include "ehead.h" - - - -void elog( x, y ) -unsigned short *x, *y; -{ -unsigned short xx[NE], z[NE], a[NE], b[NE], t[NE], qj[NE]; -long ex; -int fex; - - -if( x[NE-1] & (unsigned short )0x8000 ) - { - eclear(y); - mtherr( "elog", DOMAIN ); - return; - } -if( ecmp( x, ezero ) == 0 ) - { - einfin( y ); - eneg(y); - mtherr( "elog", SING ); - return; - } -if( ecmp( x, eone ) == 0 ) - { - eclear( y ); - return; - } - -/* range reduction: log x = log( 2**ex * m ) = ex * log2 + log m */ -efrexp( x, &fex, xx ); -/* -emov(x, xx ); -ex = xx[NX-1] & 0x7fff; -ex -= 0x3ffe; -xx[NX-1] = 0x3ffe; -*/ - -/* Adjust range to 1/sqrt(2), sqrt(2) */ -esqrt2[NE-1] -= 1; -if( ecmp( xx, esqrt2 ) < 0 ) - { - fex -= 1; - emul( xx, etwo, xx ); - } -esqrt2[NE-1] += 1; - -esub( eone, xx, a ); -if( a[NE-1] == 0 ) - { - eclear( y ); - goto logdon; - } -eadd( eone, xx, b ); -ediv( b, a, y ); /* store (x-1)/(x+1) in y */ - -emul( y, y, z ); - -emov( eone, a ); -emov( eone, b ); -emov( eone, qj ); -do - { - eadd( etwo, qj, qj ); /* 2 * i + 1 */ - emul( z, a, a ); - ediv( qj, a, t ); - eadd( t, b, b ); - } -while( ((b[NE-1] & 0x7fff) - (t[NE-1] & 0x7fff)) < NBITS ); - - -emul( b, y, y ); -emul( y, etwo, y ); - -logdon: - -/* now add log of 2**ex */ -if( fex != 0 ) - { - ex = fex; - ltoe( &ex, b ); - emul( elog2, b, b ); - eadd( b, y, y ); - } -} |