digitalmars.com                      
Last update Sun Mar 4 12:00:58 2018

math.h

fpclassify classify floating point type
isfinite test for finite
isinf test for infinity
isnan test for NaN
isnormal test for normal
signbit test sign bit of floating point value
acos arc cosine
asin arc sine
atan arc tangent
atan2 arc tangent in 4 quadrants
ceil round upwards
cos cosine
cosh hyperbolic cosine
cbrt cube root
exp ex
exp2 2x
expm1 ex - 1
fabs absolute value
floor round downwards
fmod remainder after division
frexp extract exponent and mantissa
hypot hypotenuse
ilogb logarithm base 2
ldexp n*2exp
log natural logarithm
log2 base-2 logarithm
logb logarithm base 2
log10 logarithm base 10
log1p, log1pf natural logarithm of (1 + x)
matherr, _matherrl handle errors generated by math functions
modf separate value into integral and fractional parts
nextafter next representable value
poly compute polynomial
pow xy
sin sine
sinh hyperbolic sine
sqrt square root
tan tangent
tanh hyperbolic tangent
_cabs absolute value of complex number

fpclassify

Header
math.h
Prototype
int fpclassify(x);
Description
This function, implemented as a macro, determines if a floating point value belongs to a special class. x's type is either float, double or long double. The following values can be compared to the result from fpclassify. They classify floating point values and expand to a unique constant expression of type int:

Value Meaning
FP_NANS Signalling NaN
FP_NANQ Quiet NaN
FP_NAN Quiet NaN (same as FP_NANQ)
FP_INFINITE Infinity
FP_NORMAL A number not covered by other classifications
FP_SUBNORMAL Subnormal or denormal
FP_ZERO Zero
FP_EMPTY No value
FP_UNSUPPORTED Unsupported bit pattern
Return Value
Returns a constant that reflects the class of the floating-point expression x.
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
isfinite isinf isnan isnormal

isfinite, isinf, isnan, isnormal

Header
math.h
Prototype
int isfinite(x);
int isinf(x);
int isnan(x);
int isnormal(x);
Description
Each of these takes an argument of type float, double, or long double; and determines if the argument's value is of the classified type.

Function Test
isfinite is normal, subnormal or zero
isinf is infinity
isnan is a NaN
isnormal is not zero, infinity, subnormal, or NaN
Return Value
Returns non-zero if a match, 0 if not.
Compatibility
C99 7.12.3
See Also
fpclassify

signbit

Header
math.h
Prototype
int signbit(x);
Description
Examines the sign bit of the floating-point value x (including NaNs, infinities, and zero). signbit is implemented as a macro, and x can be a float, double or long double.
Return Value
Non-zero if the sign bit is 1; zero if the sign bit is 0.
Compatibility
C99 7.12.3.6

acos

Header
math.h,
fltenv.h (Required for exception values)
Prototype
double acos(double x);
float acosf(float x);
long double acosl(long double x);
Description
The acos functions calculate the principal value of the arc cosine of x.
Return Value
The arc cosine of x.
Special Results
x return value invalid?
>1.0 NAN yes
<-1.0 NAN yes
NAN NAN yes
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
asin, atan, atan2, cos, cosh, hypot, sin, sinh, tan, tanh
Example
/* Example of acos */

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

void main() {
 double d;
 double result;

 printf("Enter a double:");
 scanf("%lg", &d);
 result = acos(d);
 printf("\nacos(%lg) = %lg\n",
    d, result);
}
Output
Enter a double:. 45
acos(0.45) = 1.10403

asin

Header
math.h
errno.h
fltenv.h (Required for exception values)
Prototype
double asin(double x);
float asinf(float x);
long double asinl(long double x);
Description
The asin functions calculate the principal value of the arcsine of x. asin calculates the arcsine of a double value; asinf calculates the arcsine of a floating-point value; and asinl calculates the arcsine of a long double value. The value of x must be between -1 and 1.
Return Value
The arcsine of x. Each function returns a value ranging from -π/2 to π/2. For asinl, if the x argument is outside the range of -1 to 1, the function returns NAN (not a number) and errno is set to EDOM, for domain error.
Special Results
x return value invalid?
±0.0 ±0.0 no
>1.0 NAN yes
<-1.0 NAN yes
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
acos atan atan2 cos cosh hypot sin sinh tan tanh Functions
Example
/* Example of asin */

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

void main() {
 double d;

 printf("Enter a double : ");
 scanf("%lg", &d);
 printf("\nasin(%g) = %g\n",
    d,asin(d));
}
Output
Enter a double :. 45
asin(0.45) = 0.466765

atan

Header
math.h
fltenv.h (Required for exception values)
Prototype
double atan(double x);
float atanf(float x);
long double atanl(long double x);
Description
The atan functions calculate the arc tangent of x.
Return Value
The arc tangent of x. This is a value in the range of -π/2 to π/2.
Special Results
x return value invalid?
±0.0 ±0.0 no
±INFINITY NAN yes
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
acos asin atan2 cos cosh hypot sin sinh tan
Example
/* Example of atan */

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

void main() {
 double d;

 printf("Enter a double : ");
 scanf("%lg", &d);
 printf("\natan(%g) = %g\n",
    d,atan(d));
}
Output
Enter a double :. 45
atan(0.45) = 0.422854

atan2

Header
math.h
fltenv.h (Required for exception values)
Prototype
double atan2(double y, double x);
float atan2f(float y, float x);
long double atan2l(long double y, long double x);
Description
The atan2 functions calculate the arc tangent of y/x.
Return Value
The arc tangent of y/x. This is a value in the range -π to π. If one argument is a NaN, that NaN is returned; if both arguments are NaNs, either one may be returned.

If both arguments are 0, these functions set errno to EDOM, print a _DOMAIN error message to stderr, and return 0.

Special Results
y x return value
±0.0 > 0.0 ±0.0
±0.0 ±0.0 ±0.0
±0.0 < 0.0 ±π
±0.0 -0.0 ±π
> 0.0 ±0.0 π/2
< 0.0 ±0.0 π/2
> 0.0 INFINITY ±0.0
±INFINITY anything ±π/2
> 0.0 -INFINITY ±π
±INFINITY INFINITY ±π/4
±INFINITY -INFINITY ±3π/4
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
acos asin atan atan2 cos cosh hypot sin sinh tan tanh
Example
/*   Example of atan2     */

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

void main() {
 double d1, d2;

 printf("Enter two doubles : ");
 scanf("%lg %lg", &d1, &d2);
 printf("\natan2(%g, %g) = %g\n",
    d1,d2,atan2(d1,d2));
}
Output
Enter two doubles :. 3 .4
atan2(0.3, 0.4) = 0.643501

cbrt

Header
math.h
fltenv.h (Required for exception values)
Prototype
double cbrt(double x);
float cbrtf(float x);
long double cbrtl(long double x);
Description
The cbrt functions calculate the cube root of x.
Return Value
The cube root of x.
Special Results
x return value invalid?
±0.0 ±0.0 no
NAN NAN yes
±∞ ±∞ no
Compatibility
C99 DOS Windows 3.x Phar Lap DOSX Win32
See Also
exp expml pow sqrt

ceil

Header
math.h
Prototype
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);
Description
Returns the value of x rounded upward to the next integer (toward positive infinity.)
Return Value
x rounded up to the next integer.
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
floor nearbyint rint rndtol rndtonl round trunc
Example
/*   Example for ceil     */

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

void main() {
 double d;

 printf("Enter a double: ");
 scanf("%lg",& d);
 printf("\nCeil (%lg) = %lg\n",
    d,ceil(d));
}
Output
Enter a double: 3.34
Ceil (3.34) = 4

cos

Header
math.h
fltenv.h (Required for exception values)
Prototype
double cos(double x);
float cosf(float x);
double cosl(double x);
Description
The cos functions calculate the cosine of x (measured in radians).
Return Value
The cosine of x. If an error occurs because x is too large, errno is set to ERANGE.
Special Results
x return value invalid?
±INFINITY NAN yes
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
acos asin sin cosh

cosh

Header
math.h
fltenv.h (Required for exception values)
Prototype
double cosh(double x);
float coshf(float x);
long double coshl(long double x);
Description
The cosh functions calculate the hyperbolic cosine of x.
Return Value
The hyperbolic sine of x. If the value of x is too large, errno is set to ERANGE.
Special Results
value of x return value invalid?
±INFINITY ±0.0 no
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
sinh cos

exp

Header
math.h
Prototype
double exp(double x);
float expf(float x);
long double expl(long double x);
Description
The exp functions calculate the value of the natural logarithm base (e) raised to the power of x.
Return Value
The value of ex. Otherwise, on overflow, returns HUGE_VAL and sets errno to ERANGE. On underflow, returns 0.
Special Results
x return value
+∞ +∞
-∞ +0.0
Compatibility
C99 DOS Windows 3.x Phar Lap DOSX Win32
See Also
exp2 expm1 log log1p log10 pow sqrt
Example
/* Example of exp */

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

int main() {
 double d;
 double result;

 printf("Enter a double:");
 scanf("%lg", &d);
 result = exp(d);
 printf("\nexp(%lg) = %lg\n",
    d,result);
 return 0;
}
Output
Enter a double: 2.34
exp(2.34) = 10.3812

exp2

Header
math.h
Prototype
double exp2(double x);
float exp2f(float x);
long double exp2l(long double x);
Description
The exp2 functions calculate the value of 2 raised to the power of x.
Return Value
The value of 2x. Otherwise, on overflow, returns HUGE_VAL and sets errno to ERANGE. On underflow, returns 0.
Special Results
x return value
+∞ +∞
-∞ +0.0
Compatibility
C99 DOS Windows 3.x Phar Lap DOSX Win32
See Also
exp expm1 log log1p log10 pow sqrt

expm1

Header
math.h
Prototype
double expm1(double x);
float expm1f(float x);
long double expm1l(long double x);
Description
Calculates the value of the natural logarithm base (e) raised to the power of x, minus 1. For very small x, expm1(x) is more accurate than exp(x) -1.
Return Value
The value of ex-1
Special Results
x ex-1
±0.0 ±0.0
+∞ +∞
-∞ -1.0
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
exp log log1p log10 pow sqrt

fabs

Header
math.h
Prototype
double fabs(double x);
float fabsf(float x);
long double fabsl(long double x);
Description
The fabs, fabsf, and fabsl functions calculate the absolute value of floating-point number x.
Return Value
The absolute value of x.
Special Results
x return value
±0.0 +0.0
±∞ +∞
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
abs copysign signbit
Example
/* Example of fabs */

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

void main() {
 double d;
 double result;

 printf("Enter a double:");
 scanf("%lg", &d);
 result = fabs(d);
 printf("\nfabs(%lg) = %lg\n",
    d,result);
}
Output
Enter a double:-2.34
fabs(-2.34) = 2.34

floor

Header
math.h
Prototype
double floor(double x);
float floorf(float x);
long double floorl(long double x);
Description
Returns the value of x rounded down to the nearest integer.
Return Value
A floating-point value that represents x rounded down to the nearest integer.
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
ceil nearbyint rint rndtol rndtonl round trunc
Example
/* Example of floor */

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

void main() {
 double d;
 printf("Enter a double: ");
 scanf("%lg", &d);
 printf("\nfloor(%g)=%g\n",
    d,floor(d));
}
Output
Enter a double: 3.14

floor(3.14)= 3

fmod

Header
math.h
fltenv.h (Required for exception values)
Prototype
double fmod(double x, double y);
float fmodf(float x, float y);
long double fmodl(long double x, long double y);
Description
These functions calculate the floating-point remainder of x/y.
Return Value
The value of x - i * y, where i is the number of times that y can be completely subtracted from x. The result has the same sign as x.
Special Results
x y return value invalid?
±0.0 not 0.0 ±0.0 no
±INFINITY anything NAN yes
anything ±0.0 NAN yes
!=±INFINITY ±INFINITY x no
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
div ldiv remainder remquo
Example
/* Example for fmod */

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

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

 r = fmod(d1, d2);
 printf("fmod(%g, %g)=%g\n",
    d1,d2,r);
}
Output
Enter two doubles:  16  7
fmod (16, 7)=2

frexp

Header
math.h
Prototype
double frexp(double x, int *exp);
float frexpf(float x, int *exp);
long double frexpl(long double x, int *exp);
Description
The frexp, frexpf, _frexpl, and frexpl functions break a floating-point number (x) into a mantisa (m) and an exponent (n), such that 0.5 <= |m| < 1.0 and x = m * 2n. The integer exponent n is stored at the location pointed to by exp.
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
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);
}
Output
Enter a double: 102
102, = 0.796875 * 2^7.

hypot

Header
math.h
Prototype
float hypotf(float x, float y);
double hypot(double x, double y);
long double hypotl(long double x, long double y);
Description
The hypot functions calculate the length of the hypotenuse of a right-angled triangle with sides of length x and y. The hypotenuse is the value of the square root of the sums of the squares of x and y: 
sqrt(x2 + y2)
Return Value
The hypotenuse of a right-angled triangle with sides x and y.
Special Results
x y return value invalid?
x +-0.0 fabs(x) no
+-∞ y +∞ no
+-∞ NAN +∞ no

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));
}
Output
Enter two doubles: 5 5
hypot (5, 5) = 7.07107

ilogb

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
C99 7.12.6.5, Win32
See Also
logb loglp logpf log10 log

ldexp

Header
math.h
Prototype
double ldexp(double n, int exp);
float ldexpf(float n, int exp);
long double ldexpl(long double n, int exp);
Description
Each function uses the following form to multiply a number by an integral power of two:

n * 2exp

Return Value
The value of n * 2exp.
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);
}
Output
Enter a double and an int: 125 5
4000 = 125 * 2^ 5.

log

Header
math.h
fltenv.h (Required for exception values)
Prototype
double log(double x);
float logf(float x);
long double logl(long double x);
Description
The log functions calculate the natural logarithm of x.
Return Value
The natural logarithm of x. If x < 0, a domain error is returned. If x == 0, a range error is returned.
Special Results
value of x return value divide by 0? invalid?
±0.0 -∞ yes no
< 0.0 NAN no yes
+∞ +∞ no no
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
loglp logpf log10
Example
/* Example for log */

#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
Enter a double: 234
log(234)= 5.45532

log2

Header
math.h
Prototype
double log2(double x);
float log2f(float x);
long double log2l(long double x);
Description
The log2 functions calculate the base-2 logarithm of x, log2x.
Return Value
The natural logarithm of x. If x < 0, a domain error is returned. If x == 0, a range error is returned.
Special Results
value of x return value divide by 0? invalid?
±0.0 -∞ yes no
< 0.0 NAN no yes
+∞ +∞ no no
Compatibility
C99 Win32
See Also
loglp logpf log10 log

logb

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
C99 Win32
See Also
ilogb loglp logpf log10 log

log10

Header
math.h
fltenv.h (Required for exception values)
Prototype
double log10(double x);
float log10f(float x);
long double log10l(long double x);
Description
The log10 functions calculate the base-10 logarithm of x.
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
value of x return value divide by 0? invalid?
±0.0 -∞ yes no
< 0.0 NAN no yes
+∞ +∞ no no
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;
}
Output
Enter a double: 234

log10(234)= 2.36922

log1p, log1pf

Header
math.h
fltenv.h (Required for exception values)
Prototype
double log1p(double x);
float log1pf(float x);
Description
The log1p and log1pf functions calculate the natural logarithm of 1 + x. For very small x, log1p(x) will be more accurate than log(1 + x).
Return Value
The natural logarithm of 1 + x.
Special Results
x log1p(x) divide by 0? invalid?
±0.0 ±0.0 no no
-1.0 -∞ yes no
<-1.0 NAN no yes
+∞ -∞ no no
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
log log10
Example
/* Example for log1p */

#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));
}
Output
Enter a double: 1.234

log1p(1.234)= 0.803794

matherr, _matherrl

Header
math.h
Prototype
int matherr(struct exception *except);
int _matherrl(struct _exceptionl *except);
Description
The matherr and _matherrl functions process errors that have been generated by math functions. The math functions call a math error function whenever an error occurs. Users can also provide their own math error functions to implement special error handling. The _matherrl is called for errors in long double math.

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
The values for type are:

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

modf

Header
math.h
Prototype
double modf(double x, double *iptr);
float modff(float x, float *iptr);
long double modfl(long double x, long double *iptr);
Description
The modf functions break x into its integral and fraction parts. each of which has the same sign as x. The integral portion is stored in the double pointed to by iptr.
Return Value
The signed fractional portion of x.
Special Results
x return value *iptr after
±INFINITY ±0.0 ±INFINITY
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
Example
/* Example for modf */

#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);
}
Output
Enter a double: 123.456
For 123.456, the fractional part is 0.456,
and the integral part is 123.

nextafter

Header
fltpnt.h
Prototype
double nextafter(double x, double y);
float nextafterf(float x, float y)
long double nextafterl(long double x, long double y);
Description
Calculates the next representable value after x in the direction of y.
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 */

#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);
}
Output
Enter two doubles: 1 2
nextafter(1, 2)= 1.0000000000000002

poly

Header
math.h
Prototype
double poly(double x, int deg, double coeff[]);
long double polyl(long double x, int deg, long double coeff[]);
Description
poly and polyl evaluate a polynomial of the form:

(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 */

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

pow

Header
math.h
Prototype
double pow(double x, double y);
float powf(float x, float y);
long double powl(long double x, long double y);
Description
The pow functions calculate xy.
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
x 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 integer +INFINITY no no
-INFINITY odd integer<0.0 -0.0 no no
-INFINITY <0.0, not odd integer +0.0 no no
±1.0 ±INFINITY NAN no yes
<0.0 finite, nonintegral NAN no yes
±0.0 odd integer <0.0 ±INFINITY yes no
±0.0 <0.0, not odd integer +INFINITY yes no
±0.0 odd integer>0.0 ±0.0 no no
±0.0 >0.0, not odd integer +0.0 no no
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
exp log log1p log10 sqrt
Example
/* Example for pow */

#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));
}
Output
Enter two doubles: 2 16

pow(2, 16)= 65536

sin

Header
math.h
fltenv.h (Required for exception values)
Prototype
double sin(double x);
float sinf(float x);
long double sinl(long double x);
Description
The sin functions calculate the sine of x (measured in radians).
Return Value
The sine of x. If an error occurs because x is too large, errno is set to ERANGE.
Special Results
x return value invalid?
±0.0 ±0.0 no
±INFINITY NAN yes
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
acos asin cos sinh
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

sinh

Header
math.h
fltenv.h (Required for exception values)
Prototype
double sinh(double x);
float sinhf(float x);
long double sinhl(long double x);
Description
The sinh functions calculate the hyperbolic sine of x.
Return Value
The hyperbolic sine of x. If the value of x is too large, errno is set to ERANGE.
Special Results

x return value invalid?
±0.0 ±0.0 no
±∞ ±∞ no
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
cosh sin
Example
/* Example of 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));
}
Output
Enter a double: 12

sinh(12)= 81377.4

sqrt

Header
math.h
fltenv.h (Required for exception values)
Prototype
double sqrt(double x);
float sqrtf(float x);
long double sqrtl(long double x);
Description
The sqrt functions calculate the square root of x.
Return Value
The square root of x.
Special Results
x return value invalid?
0.0 0.0 no
<0.0 NAN yes
NAN NAN yes
+∞ +∞ no
Compatibility
C99 DOS Windows 3.x Phar Lap DOSX Win32
See Also
exp expml pow cbrt
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
Enter a double: 81
sqrt(81)= 9

tan

Header
math.h
fltenv.h (Required for exception values)
Prototype
double tan(double x);
float tanf(float x);
long double tanl(long double x);
Description
The tan functions calculate the tangent of x (measured in radians).
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
x return value invalid?
±0.0 ±0.0 no
±INFINITY NAN yes
Compatibility
DOS Windows 3.x Phar Lap DOSX Win32
See Also
acos tanh
Example
/* Example of tan */

#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));
}
Output
Enter a double: 100

tan(100)=-0.587214

tanh

Header
math.h
Prototype
double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);
Description
The tanh functions calculate the hyperbolic tangent of x.
Return Value
The hyperbolic tangent of x.
Special Results
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

_cabs, _cabsl

Header
math.h
Prototype
double _cabs(struct _complex z);
long double _cabsl(struct _complexl z);
Description
The _cabs and _cabsl functions calculate the absolute value of the complex number stored in the z structure. This structure is composed of a real component x and an imaginary component y. In the _cabs function, x and y are double values; in the _cabsl function, x and y are long double values.
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);
}
Output
cabs of (3,1i) = 3.16228
Home | Compiler & Tools | IDDE Reference | STL | Search | Download | Forums