C <math.h> Library Function: The C math.h library function defines various mathematical functions and one macro. All the functions available in this library take double as an argument and return double as the result.
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
#include <stdio.h>
#include <math.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);
}
Output
value1 = 2.0
value2 = 2.0
value3 = -2.0
value4 = -2.0
C math.h Library Function
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
#include<stdio.h>
#include<math.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);
}
Output
Value1 = 1.0
Value2 = 1.0
Value3 = -3.0
Value4 = -3.0
double fabs(double x)
The C library function double fabs(double x) returns the absolute value of x.
Syntax : double fabs(double x)
Example
#include<stdio.h>
#include<math.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);
}
Output
The absolute value of 1234 is 1234.000000
The absolute value of -344 is 344.000000
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
#include<stdio.h>
#include<math.h>
int main()
{
double x, ret;
x = 2.7;
/*finding log(2.7) */
ret = log(x);
printf("log(%lf) = %lf", x, ret);
return(0);
}
Output
log(2.700000) = 0.993252
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
#include<stdio.h>
#include<math.h>
int main()
{
double x, ret;
x = 10000;
/* finding value of log1010000 */
ret = log10(x);
printf("log10(%lf) = %lf\n", x, ret);
return(0);
}
Output
log10(10000.000000) = 4.000000
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
#include<stdio.h>
#include<math.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
The remainder of 8.200000 / 3 is 2.200000
The remainder of 8.200000 / 5.700000 is 2.500000
double sqrt(double x)
The C library function double sqrt(double x) returns the square root of x.
Syntax : double sqrt(double x)
Example
#include<stdio.h>
#include<math.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);
}
Output
The square root of 225.000000 is 15.000000
The square root of 300.000000 is 17.320508
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
#include<stdio.h>
#include<math.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);
}
Output
Value 8.0 ^ 3 = 512.000000
Value 3.05 ^ 1.98 = 9.097324
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
#include<stdio.h>
#include<math.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);
}
Output
Integral part = 8.000000
Fraction Part = 0.123456
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
#include<stdio.h>
#include<math.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);
}
Output
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
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)
Example
#include<stdio.h>
#include<math.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);
}
Output
The cosine of 60.000000 is 0.500000 degrees
The cosine of 90.000000 is 0.000000 degrees
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)
Example
#include<stdio.h>
#include<math.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);
}
Output
The arc cosine of 0.900000 is 25.855040 degrees.
double tanh(double x)
The C library function double tanh(double x) returns the hyperbolic tangent of x.
Syntax : double tanh(double x)
Example
#include<stdio.h>
#include<math.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);
}
Output
The hyperbolic tangent of 0.500000 is 0.462117 degrees