# C math.h Library Function

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