C Math Functions
1. double ceil (double x)
The C library function double ceil (double x) returns the smallest integer value greater than or equal to x.
Syntax
double ceil(double x);
Example
C
// C code to illustrate // the use of ceil function. #include <math.h> #include <stdio.h> int main() { float val1, val2, val3, val4; val1 = 1.6; val2 = 1.2; val3 = -2.8; val4 = -2.3; printf ( "value1 = %.1lf\n" , ceil (val1)); printf ( "value2 = %.1lf\n" , ceil (val2)); printf ( "value3 = %.1lf\n" , ceil (val3)); printf ( "value4 = %.1lf\n" , ceil (val4)); return (0); } |
value1 = 2.0 value2 = 2.0 value3 = -2.0 value4 = -2.0
2. double floor(double x)
The C library function double floor(double x) returns the largest integer value less than or equal to x.
Syntax
double floor(double x);
Example
C
// C code to illustrate // the use of floor function #include <math.h> #include <stdio.h> int main() { float val1, val2, val3, val4; val1 = 1.6; val2 = 1.2; val3 = -2.8; val4 = -2.3; printf ( "Value1 = %.1lf\n" , floor (val1)); printf ( "Value2 = %.1lf\n" , floor (val2)); printf ( "Value3 = %.1lf\n" , floor (val3)); printf ( "Value4 = %.1lf\n" , floor (val4)); return (0); } |
Value1 = 1.0 Value2 = 1.0 Value3 = -3.0 Value4 = -3.0
3. double fabs(double x)
The C library function double fabs(double x) returns the absolute value of x.
Syntax
syntax : double fabs(double x)
Example
C
// C code to illustrate // the use of fabs function #include <math.h> #include <stdio.h> int main() { int a, b; a = 1234; b = -344; printf ( "The absolute value of %d is %lf\n" , a, fabs (a)); printf ( "The absolute value of %d is %lf\n" , b, fabs (b)); return (0); } |
The absolute value of 1234 is 1234.000000 The absolute value of -344 is 344.000000
4. double log(double x)
The C library function double log(double x) returns the natural logarithm (base-e logarithm) of x.
Syntax
double log(double x)
Example
C
// C code to illustrate // the use of log function #include <math.h> #include <stdio.h> int main() { double x, ret; x = 2.7; /* finding log(2.7) */ ret = log (x); printf ( "log(%lf) = %lf" , x, ret); return (0); } |
log(2.700000) = 0.993252
5. double log10(double x)
The C library function double log10(double x) returns the common logarithm (base-10 logarithm) of x.
Syntax
double log10(double x);
Example
C
// C code to illustrate // the use of log10 function #include <math.h> #include <stdio.h> int main() { double x, ret; x = 10000; /* finding value of log1010000 */ ret = log10 (x); printf ( "log10(%lf) = %lf\n" , x, ret); return (0); } |
log10(10000.000000) = 4.000000
6. double fmod(double x, double y)
The C library function double fmod(double x, double y) returns the remainder of x divided by y.
Syntax
double fmod(double x, double y)
Example
C
// C code to illustrate // the use of fmod function #include <math.h> #include <stdio.h> int main() { float a, b; int c; a = 8.2; b = 5.7; c = 3; printf ( "Remainder of %f / %d is %lf\n" , a, c, fmod (a, c)); printf ( "Remainder of %f / %f is %lf\n" , a, b, fmod (a, b)); return (0); } |
Output
Remainder of 8.200000 / 3 is 2.200000 Remainder of 8.200000 / 5.700000 is 2.500000
7. double sqrt(double x)
The C library function double sqrt(double x) returns the square root of x.
Syntax
double sqrt(double x);
Example
C
// C code to illustrate // the use of sqrt function #include <math.h> #include <stdio.h> int main() { printf ( "Square root of %lf is %lf\n" , 225.0, sqrt (225.0)); printf ( "Square root of %lf is %lf\n" , 300.0, sqrt (300.0)); return (0); } |
Square root of 225.000000 is 15.000000 Square root of 300.000000 is 17.320508
8. double pow(double x, double y)
The C library function double pow(double x, double y) returns x raised to the power of y i.e. xy.
Syntax
double pow(double x, double y);
Example
C
// C code to illustrate // the use of pow function #include <math.h> #include <stdio.h> int main() { printf ( "Value 8.0 ^ 3 = %lf\n" , pow (8.0, 3)); printf ( "Value 3.05 ^ 1.98 = %lf" , pow (3.05, 1.98)); return (0); } |
Value 8.0 ^ 3 = 512.000000 Value 3.05 ^ 1.98 = 9.097324
9. double modf(double x, double *integer)
The C library function double modf(double x, double *integer) returns the fraction component (part after the decimal), and sets integer to the integer component.
Syntax
double modf(double x, double *integer)
Example
C
// C code to illustrate // the use of modf function #include <math.h> #include <stdio.h> int main() { double x, fractpart, intpart; x = 8.123456; fractpart = modf (x, &intpart); printf ( "Integral part = %lf\n" , intpart); printf ( "Fraction Part = %lf \n" , fractpart); return (0); } |
Integral part = 8.000000 Fraction Part = 0.123456
10. double exp(double x)
The C library function double exp(double x) returns the value of e raised to the xth power.
Syntax
double exp(double x);
Example
C
// C code to illustrate // the use of exp function #include <math.h> #include <stdio.h> int main() { double x = 0; printf ( "The exponential value of %lf is %lf\n" , x, exp (x)); printf ( "The exponential value of %lf is %lf\n" , x + 1, exp (x + 1)); printf ( "The exponential value of %lf is %lf\n" , x + 2, exp (x + 2)); return (0); } |
The exponential value of 0.000000 is 1.000000 The exponential value of 1.000000 is 2.718282 The exponential value of 2.000000 is 7.389056
11. double cos(double x)
The C library function double cos(double x) returns the cosine of a radian angle x.
Syntax
double cos(double x);
The same syntax can be used for other trigonometric functions like sin, tan, etc.
Example
C
// C code to illustrate // the use of cos function #include <math.h> #include <stdio.h> #define PI 3.14159265 int main() { double x, ret, val; x = 60.0; val = PI / 180.0; ret = cos (x * val); printf ( "The cosine of %lf is %lf degrees\n" , x, ret); x = 90.0; val = PI / 180.0; ret = cos (x * val); printf ( "The cosine of %lf is %lf degrees\n" , x, ret); return (0); } |
The cosine of 60.000000 is 0.500000 degrees The cosine of 90.000000 is 0.000000 degrees
12. double acos(double x)
The C library function double acos(double x) returns the arc cosine of x in radians.
Syntax
double acos(double x);
The same syntax can be used for other arc trigonometric functions like asin, atan etc.
Example
C
// C code to illustrate // the use of acos function #include <math.h> #include <stdio.h> #define PI 3.14159265 int main() { double x, ret, val; x = 0.9; val = 180.0 / PI; ret = acos (x) * val; printf ( "The arc cosine of %lf is %lf degrees" , x, ret); return (0); } |
The arc cosine of 0.900000 is 25.841933 degrees
13. double tanh(double x)
The C library function double tanh(double x) returns the hyperbolic tangent of x.
Syntax
double tanh(double x);
The same syntax can be used for other hyperbolic trigonometric functions like sinh, cosh etc.
Example
C
// C code to illustrate // the use of tanh function #include <math.h> #include <stdio.h> int main() { double x, ret; x = 0.5; ret = tanh (x); printf ( "The hyperbolic tangent of %lf is %lf degrees" , x, ret); return (0); } |
The hyperbolic tangent of 0.500000 is 0.462117 degrees
C Library math.h Functions
The math.h header defines various C mathematical functions and one macro. All the functions available in this library take double as an argument and return double as the result. Let us discuss some important C math functions one by one.