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/* isnan()
* signbit()
* isfinite()
*
* Floating point numeric utilities
*
*
*
* SYNOPSIS:
*
* double ceil(), floor(), frexp(), ldexp();
* int signbit(), isnan(), isfinite();
* double x, y;
* int expnt, n;
*
* y = floor(x);
* y = ceil(x);
* y = frexp( x, &expnt );
* y = ldexp( x, n );
* n = signbit(x);
* n = isnan(x);
* n = isfinite(x);
*
*
*
* DESCRIPTION:
*
* All four routines return a double precision floating point
* result.
*
* floor() returns the largest integer less than or equal to x.
* It truncates toward minus infinity.
*
* ceil() returns the smallest integer greater than or equal
* to x. It truncates toward plus infinity.
*
* frexp() extracts the exponent from x. It returns an integer
* power of two to expnt and the significand between 0.5 and 1
* to y. Thus x = y * 2**expn.
*
* ldexp() multiplies x by 2**n.
*
* signbit(x) returns 1 if the sign bit of x is 1, else 0.
*
* These functions are part of the standard C run time library
* for many but not all C compilers. The ones supplied are
* written in C for either DEC or IEEE arithmetic. They should
* be used only if your compiler library does not already have
* them.
*
* The IEEE versions assume that denormal numbers are implemented
* in the arithmetic. Some modifications will be required if
* the arithmetic has abrupt rather than gradual underflow.
*/
/*
Cephes Math Library Release 2.3: March, 1995
Copyright 1984, 1995 by Stephen L. Moshier
*/
#include <math.h>
#ifdef UNK
/* ceil(), floor(), frexp(), ldexp() may need to be rewritten. */
#undef UNK
#if BIGENDIAN
#define MIEEE 1
#else
#define IBMPC 1
#endif
#endif
/* Return 1 if the sign bit of x is 1, else 0. */
int signbit(x)
double x;
{
union
{
double d;
short s[4];
int i[2];
} u;
u.d = x;
if( sizeof(int) == 4 )
{
#ifdef IBMPC
return( u.i[1] < 0 );
#endif
#ifdef DEC
return( u.s[3] < 0 );
#endif
#ifdef MIEEE
return( u.i[0] < 0 );
#endif
}
else
{
#ifdef IBMPC
return( u.s[3] < 0 );
#endif
#ifdef DEC
return( u.s[3] < 0 );
#endif
#ifdef MIEEE
return( u.s[0] < 0 );
#endif
}
}
/* Return 1 if x is a number that is Not a Number, else return 0. */
int isnan(x)
double x;
{
#ifdef NANS
union
{
double d;
unsigned short s[4];
unsigned int i[2];
} u;
u.d = x;
if( sizeof(int) == 4 )
{
#ifdef IBMPC
if( ((u.i[1] & 0x7ff00000) == 0x7ff00000)
&& (((u.i[1] & 0x000fffff) != 0) || (u.i[0] != 0)))
return 1;
#endif
#ifdef DEC
if( (u.s[1] & 0x7fff) == 0)
{
if( (u.s[2] | u.s[1] | u.s[0]) != 0 )
return(1);
}
#endif
#ifdef MIEEE
if( ((u.i[0] & 0x7ff00000) == 0x7ff00000)
&& (((u.i[0] & 0x000fffff) != 0) || (u.i[1] != 0)))
return 1;
#endif
return(0);
}
else
{ /* size int not 4 */
#ifdef IBMPC
if( (u.s[3] & 0x7ff0) == 0x7ff0)
{
if( ((u.s[3] & 0x000f) | u.s[2] | u.s[1] | u.s[0]) != 0 )
return(1);
}
#endif
#ifdef DEC
if( (u.s[3] & 0x7fff) == 0)
{
if( (u.s[2] | u.s[1] | u.s[0]) != 0 )
return(1);
}
#endif
#ifdef MIEEE
if( (u.s[0] & 0x7ff0) == 0x7ff0)
{
if( ((u.s[0] & 0x000f) | u.s[1] | u.s[2] | u.s[3]) != 0 )
return(1);
}
#endif
return(0);
} /* size int not 4 */
#else
/* No NANS. */
return(0);
#endif
}
/* Return 1 if x is not infinite and is not a NaN. */
int isfinite(x)
double x;
{
#ifdef INFINITIES
union
{
double d;
unsigned short s[4];
unsigned int i[2];
} u;
u.d = x;
if( sizeof(int) == 4 )
{
#ifdef IBMPC
if( (u.i[1] & 0x7ff00000) != 0x7ff00000)
return 1;
#endif
#ifdef DEC
if( (u.s[3] & 0x7fff) != 0)
return 1;
#endif
#ifdef MIEEE
if( (u.i[0] & 0x7ff00000) != 0x7ff00000)
return 1;
#endif
return(0);
}
else
{
#ifdef IBMPC
if( (u.s[3] & 0x7ff0) != 0x7ff0)
return 1;
#endif
#ifdef DEC
if( (u.s[3] & 0x7fff) != 0)
return 1;
#endif
#ifdef MIEEE
if( (u.s[0] & 0x7ff0) != 0x7ff0)
return 1;
#endif
return(0);
}
#else
/* No INFINITY. */
return(1);
#endif
}
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