summaryrefslogtreecommitdiff
path: root/libm/ldouble/cbrtl.c
diff options
context:
space:
mode:
Diffstat (limited to 'libm/ldouble/cbrtl.c')
-rw-r--r--libm/ldouble/cbrtl.c143
1 files changed, 0 insertions, 143 deletions
diff --git a/libm/ldouble/cbrtl.c b/libm/ldouble/cbrtl.c
deleted file mode 100644
index 89ed11a06..000000000
--- a/libm/ldouble/cbrtl.c
+++ /dev/null
@@ -1,143 +0,0 @@
-/* cbrtl.c
- *
- * Cube root, long double precision
- *
- *
- *
- * SYNOPSIS:
- *
- * long double x, y, cbrtl();
- *
- * y = cbrtl( x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns the cube root of the argument, which may be negative.
- *
- * Range reduction involves determining the power of 2 of
- * the argument. A polynomial of degree 2 applied to the
- * mantissa, and multiplication by the cube root of 1, 2, or 4
- * approximates the root to within about 0.1%. Then Newton's
- * iteration is used three times to converge to an accurate
- * result.
- *
- *
- *
- * ACCURACY:
- *
- * Relative error:
- * arithmetic domain # trials peak rms
- * IEEE .125,8 80000 7.0e-20 2.2e-20
- * IEEE exp(+-707) 100000 7.0e-20 2.4e-20
- *
- */
-
-
-/*
-Cephes Math Library Release 2.2: January, 1991
-Copyright 1984, 1991 by Stephen L. Moshier
-Direct inquiries to 30 Frost Street, Cambridge, MA 02140
-*/
-
-
-#include <math.h>
-
-static long double CBRT2 = 1.2599210498948731647672L;
-static long double CBRT4 = 1.5874010519681994747517L;
-static long double CBRT2I = 0.79370052598409973737585L;
-static long double CBRT4I = 0.62996052494743658238361L;
-
-#ifdef ANSIPROT
-extern long double frexpl ( long double, int * );
-extern long double ldexpl ( long double, int );
-extern int isnanl ( long double );
-#else
-long double frexpl(), ldexpl();
-extern int isnanl();
-#endif
-
-#ifdef INFINITIES
-extern long double INFINITYL;
-#endif
-
-long double cbrtl(x)
-long double x;
-{
-int e, rem, sign;
-long double z;
-
-
-#ifdef NANS
-if(isnanl(x))
- return(x);
-#endif
-#ifdef INFINITIES
-if( x == INFINITYL)
- return(x);
-if( x == -INFINITYL)
- return(x);
-#endif
-if( x == 0 )
- return( x );
-if( x > 0 )
- sign = 1;
-else
- {
- sign = -1;
- x = -x;
- }
-
-z = x;
-/* extract power of 2, leaving
- * mantissa between 0.5 and 1
- */
-x = frexpl( x, &e );
-
-/* Approximate cube root of number between .5 and 1,
- * peak relative error = 1.2e-6
- */
-x = (((( 1.3584464340920900529734e-1L * x
- - 6.3986917220457538402318e-1L) * x
- + 1.2875551670318751538055e0L) * x
- - 1.4897083391357284957891e0L) * x
- + 1.3304961236013647092521e0L) * x
- + 3.7568280825958912391243e-1L;
-
-/* exponent divided by 3 */
-if( e >= 0 )
- {
- rem = e;
- e /= 3;
- rem -= 3*e;
- if( rem == 1 )
- x *= CBRT2;
- else if( rem == 2 )
- x *= CBRT4;
- }
-else
- { /* argument less than 1 */
- e = -e;
- rem = e;
- e /= 3;
- rem -= 3*e;
- if( rem == 1 )
- x *= CBRT2I;
- else if( rem == 2 )
- x *= CBRT4I;
- e = -e;
- }
-
-/* multiply by power of 2 */
-x = ldexpl( x, e );
-
-/* Newton iteration */
-
-x -= ( x - (z/(x*x)) )*0.3333333333333333333333L;
-x -= ( x - (z/(x*x)) )*0.3333333333333333333333L;
-
-if( sign < 0 )
- x = -x;
-return(x);
-}