math.h

math.h

Prototype

double frexp(double x, int *exp);
float frexpf(float x, int *exp);
long double frexpl(long double x, int *exp);

Description

Return Value

These functions return the mantissa. If x is 0, the functions return 0 for both the mantissa and the exponent. There is no error return.

Special Results

value of x 	return value 	*exp after?

±0.0 		±0.0 		+0.0 
±INFINITY 	±INFINITY 	? 
NAN 		NAN 		? 

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

ldexp

Example

	/* 	Example for frexp */

	#include <stdio.h>
	#include <stdio.h>
	#include <math.h>

	void main() 
	{ 
	   int e; 
	   double d, r; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   r = frexp (d, &e); 
	   printf("%g, = %g * 2^%d.\n", d, r, e); 
	} 

Enter a double: 102
102, = 0.796875 * 2^7.

Header

math.h

Prototype

int ilogb(double x);
int ilogbf(float x);
int ilogbl(long double x);

Description

Extracts the exponent of x as a signed integral value. If x is not a special value, the result is the same as if logb was called instead and the result was cast to int.

Return Value

The signed exponent of the argument.

Special Results

x	Return value	Range error?
0	FP_ILOGB0	yes
±∞	+∞	no
NAN	FP_ILOGBNAN	no

Compatibility

See Also

Header

Prototype

double ldexp(double n, int exp);
float ldexpf(float n, int exp);
long double ldexpl(long double n, int exp);

Description

n * 2^exp

Return Value

The value of n * 2^exp.

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

frexp

Example

	/* 	Example for ldexp */

	#include <stdlib.h> 
	#include <stdio.h> 
	#include <math.h>

	void main() 
	{ 
	   int e; 
	   double d, r; 

	   printf("Enter a double and an int: "); 
	   scanf("%lg %d", &d, &e); 
	   r = ldexp (d, e); 
	   printf("%g = %g * 2^%d.\n\n", r, d, e); 
	} 

Enter a double and an int: 125 5
4000 = 125 * 2^ 5.

Header

Prototype

Description

Return Value

Special Results

Compatibility

See Also

Example

	/* 	Example for log 
		Also demonstrates logl 
	*/

	#include <stdlib.h> 
	#include <stdio.h> 
	#include <math.h>

	void main() 
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\nlog(%g)=%g\n\n", d, log(d)); 
	} 

Output

log(234)= 5.45532

Header

Prototype

Description

Return Value

Special Results

Compatibility

See Also

Header

math.h

Prototype

double logb(double x);
float logbf(float x);
long double logbl(long double x);

Description

Extracts the exponent of x as a signed integral value. If x is subnormal, it is treated as if it were normalized. For a positive, finite x:

	1 <= x * FLT_RADIX-logb(x) < FLT_RADIX 
	

Return Value

The signed exponent of the argument.

Special Results

x	Return value	Divide by 0?
±∞	+∞	no
±0.0	-∞	yes

Compatibility

See Also

Header

Prototype

double log10(double x);
float log10f(float x);
long double log10l(long double x);

Description

Return Value

The base-10 logarithm of x. If x < 0, a domain error is returned. If x == 0, a range error is returned.

Special Results

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

log
log1p

Example

	/* Example for log10 */

	#include <stdlib.h>
	#include <stdio.h> 
	#include <math.h> 

	int main()
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\nlog10(%g)=%g\n\n", d, log10(d));
	   return 0; 
	} 

Enter a double: 234

log10(234)= 2.36922

Header

Prototype

double log1p(double x);
float log1pf(float x);

Description

Return Value

The natural logarithm of 1 + x.

Special Results

Compatibility

See Also

log
log10

Example

	/* 	Example for log1p 
		Also demonstrates loglpf 
	*/

	#include <stdlib.h> 
	#include <stdio.h> 
	#include <math.h>

	void main() 
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\nlog1p(%g)=%g\n\n", d, log1p(d)); 
	} 

Enter a double: 1.234

log1p(1.234)= 0.803794

Header

Prototype

int matherr(struct exception *except);
int _matherrl(struct _exceptionl *except);

Description

A pointer to the exception structure will be passed to a user-supplied math error function when an error occurs. The exception structures, _exception and _exceptionl are defined in math.h. They have the following elements:

Element/Description

int type

Exception type (see the following table)

char *name

Function name where error occurred

double arg1, arg2

Function arguments

double retval

Value returned by function

Value/Description

_DOMAIN

Argument domain error

_SING

Argument singularity

_OVERFLOW

Overflow range error

_PLOSS

Partial loss of significance

_TLOSS

Total loss of significance

_UNDERFLOW

Underflow range error

Return Value

These functions return 0 to indicate an error, non-zero for success.

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

The other math functions

Header

Prototype

double modf(double x, double *iptr);
float modff(float x, float *iptr);
long double modfl(long double x, long double *iptr);

Description

Return Value

The signed fractional portion of x.

Special Results

value of x 	return value 	*iptr after
±INFINITY 	±0.0 		±INFINITY 

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

Example

	/* 	Example for modf
		Also demonstrates modfl 
	*/

	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h> 

	void main()
	{ 
	   double d, frac, intr; 

	   printf("Enter a double: ");
	   scanf("%lg", &d); 
	   frac = modf (d, &intr);
	   printf("\nFor %g, the fractional part is 
		  %g,\nand the integral part is " 
		  "%g.\n", d, frac, intr); 
	} 

Enter a double: 123.456

For 123.456, the fractional part is 0.456,
and the integral part is 123.

Header

Prototype

double nextafter(double x, double y);
float nextafterf(float x, float y)
long double nextafterl(long double x, long double y);

Description

Return Value

If y is greater than x, the result will be the next largest floating-point value; if y is less than x, the result will be the next smallest value. If x and y are equal, the result is x. The FE_INEXACT and FE_OVERFLOW exceptions will be raised if x is finite and the function result is infinite. The FE_INEXACT and FE_UNDERFLOW exceptions will be raised if the function value is subnormal, and x is not equal to y.

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

Example

	/* 	Example for nextafter
		Also demonstrates nextafterf 
	*/

	#include <stdio.h>
	#include <stdlib.h> 
	#include <math.h>
	#include <fltpnt.h>

	void main()
	{ 
	   double d1, d2, r; 
	   printf("Enter two doubles: ");
	   scanf("%lg %lg", &d1, &d2); 

	   r = nextafter(d1, d2);
	   printf("nextafter(%g, %g)=%. 16f\n", d1, 
	   d2, r);
	} 

Enter two doubles: 1 2
nextafter(1, 2)= 1.0000000000000002

Header

Prototype

double poly(double x, int deg, double coeff[]);
long double polyl(long double x, int deg, long double coeff[]);

Description

(coeff[deg] * x + coeff [deg-1]) * x +...+ coeff[0].

Argument x is the base value; deg is the maximum degree, and coeff is an array containing the coefficients of the values.

The polyl function is the long double version of poly.

Return Value

Both functions return the calculated value of the polynomial.

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

Example

	/* 	Example for poly
		Also demonstrates polyl 
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <math.h>

	void main()
	{ 
	   double coeff[4], x = 1.2, y; 
	   
	   coeff[0] = 0.0;
	   coeff[1] = 1.0; 
	   coeff[2] = 2.0;
	   coeff[3] = 3.0; 

	   y = poly(x, 3, coeff); 

	   printf("poly(%g, 3, {%g, %g, %g, %g}) = 
		     %g\n", x, coeff[0], coeff[1], 
		     coeff[2], coeff[3], y);
	} 

poly(1.2, 3, {0, 1, 2, 3}) = 9.264

Header

Prototype

double pow(double x, double y);
float powf(float x, float y);
long double powl(long double x, long double y);

Description

Return Value

x raised to the power of y. If an overflow occurs, the pow functions set errno to ERANGE and return _HUGE_VAL or _LHUGE_VAL (if the return type is long double).

Special Results

value of x	value of y	return value	div 0	inv

anything 	±0.0 		1.0 		no 	no 
|x| > 1 	+INFINITY 	+INFINITY 	no 	no 
|x| < 1 	+INFINITY 	+0.0 		no 	no 
|x| > 1 	-INFINITY 	+0.0 		no 	no 
|x| < 1 	-INFINITY 	+INFINITY 	no 	no 
+INFINITY 	y > 0.0 	+INFINITY 	no 	no 
+INFINITY 	y < 0.0 	+0.0 		no 	no 
-INFINITY 	odd integer>0.0	-INFINITY 	no 	no 
-INFINITY  	>0.0,not odd	+INFINITY 	no 	no
		integer 
-INFINITY 	odd integer<0.0 -0.0 		no 	no 
-INFINITY 	<0.0, not odd 	+0.0 		no 	no 
		integer 
±1.0 		±INFINITY 	NAN 		no 	yes 
<0.0 		finite, 	NAN 		no 	yes
		nonintegral  
±0.0 		odd integer <0.0±INFINITY 	yes 	no 
±0.0 		<0.0, not odd 	+INFINITY 	yes 	no
		integer 
±0.0 		odd integer>0.0 ±0.0 		no 	no 
±0.0 		>0.0, not odd 	+0.0 		no 	no 
		integer 

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

exp
log
log1p
log10
sqrt

Example

	/* 	Example for pow
		Also demonstrates powl 
	*/

	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h>

	void main()
	{ 

	   double d1, d2; 

	   printf("Enter two doubles: ");
	   scanf("%lg %lg", &d1, &d2); 
	   printf("\npow(%g, %g)=%g\n", d1, d2,
		    pow (d1, d2)); 
	} 

Enter two doubles: 2 16

pow(2, 16)= 65536

Header

Prototype

Description

Return Value

Special Results

value of x 	return value 		invalid? 
±0.0 		±0.0 			no 
±INFINITY 	NAN 			yes 

Compatibility

See Also

Example

	/* 	Example of sin()
	*/

	#include <stdlib.h>
	#include <stdio.h> 
	#include <math.h> 

	void main()
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\nsin(%g)=%g\n", d, sin(d)); 
	} 

Output

Enter a double: 100

sin(100)=-0.506366 

Header

Prototype

double sinh(double x);
float sinhf(float x);
long double sinhl(long double x);

Description

Return Value

The hyperbolic sine of x. If the value of x is too large, errno is set to ERANGE.

Special Results

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

cosh
sin

Example

	/* 	Example of sinh 
		Also demonstrates sinh 
	*/

	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h>

	void main() 
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\nsinh(%g)=%g\n", d, sinh (d)); 
	} 

Enter a double: 12

sinh(12)= 81377.4

Header

Prototype

Description

Return Value

Special Results

Compatibility

See Also

Example

	/* 	Example of sqrt */

	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h>

	int main()
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\nsqrt(%g)=%g\n", d, sqrt(d)); 

	   return 0;
	} 

Output

sqrt(81)= 9

Header

Prototype

double tan(double x);
float tanf(float x);
long double tanl(long double x);

Description

Return Value

The tangent of x.

If x is too large, a partial loss of significance may occur. In this case, the tan functions set global variable errno to ERANGE and generate a _PLOSS error. If x is so large that significance is totally lost, tan functions print a _TLOSS error message to stderr, set errno to ERANGE, and return 0.

Special Results

value of x	return value	invalid?
±0.0 		±0.0 		no 
±INFINITY 	NAN 		yes 

DOS Windows 3.x Phar Lap DOSX Win32

See Also

acos
tanh

Example

	/* 	Example of tan 
		Also demonstrates tanl 
	
	*/
	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h>

	void main() 
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\ntan(%g)=%g\n", d, tan (d)); 
	} 

Enter a double: 100

tan(100)=-0.587214

Header

Prototype

double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);

Description

Return Value

The hyperbolic tangent of x.

Special Results

value of x 	return value 	invalid?
±0.0 		±0.0 		no 
±INFINITY 	±1.0 		no

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

acos
tan

Example

	/* 	Example of tanh 	*/

	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h>

	void main() 
	{ 
	   double d; 

	   printf("Enter a double: "); 
	   scanf("%lg", &d); 
	   printf("\ntanh(%g)=%g\n", d, tanh(d)); 
	} 

Output

Enter a double: 3

tanh(3)= 0.995055 

Header

Prototype

double _cabs(struct _complex z);
long double _cabsl(struct _complexl z);

Description

Synonym

Function: cabs, cabl
Argument: complex, complexl

Return Value

The absolute value of z. If an overflow occurs, these functions return HUGE_VAL, and set variable errno to ERANGE.

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

abs
fabs

Example

	/* 	Example for cabs 	*/

	#include <math.h> 
	#include <stdio.h> 
	#include <stdlib.h>
 
	void main() 
	{
 
	   struct _complex z; 
	   double retval; 

	   z. x = 3.0; 
	   z. y = 1.0; 
	   retval = _cabs(z); 
	   printf("cabs of (%g,%gi) = %g", z. x, z. y, 
		     retval); 
	}

cabs of (3,1i) = 3.16228

Header

Prototype

float hypotf(float x, float y);
double hypot(double x, double y);
long double hypotl(long double x, long double y);

Description

	sqrt(x2 + y2)

Return Value

Special Results

Note that hypot(x,y), hypot(y,x) and hypot(x,-y) are equivalent.

Compatibility

ANSI C99, DOS, Windows 3.x, Phar Lap, DOSX, Win32

See Also

cosh
sinh
tanh
ANSI C99 7.12.7.3, F.9.4.3

Example

	/* 	Example for hypot */

	#include <stdio.h> 
	#include <math.h>

	void main() 
	{ 
	   double d1, d2; 

	   printf("Enter two doubles: "); 
	   scanf("%Lg %Lg", &d1, &d2); 
	   printf("\nhypot (%g, %g) = %g\n", d1, d2, 
		    hypot (d1, d2)); 
	} 

Enter two doubles: 5 5
hypot (5, 5) = 7.07107