C library - tanh() function

---

---

The C library tanh() function accepts the parameter(x) of type double returns the hyperbolic tangent of x.

The parameter passed to tanh() can be any real number, either its positive or negative. The real life uses of tanh() function − Neural Network, Signal Processing, statistics and data analysis.

Syntax

Following is the syntax of the C library function tanh() −

double tanh(double x)

Parameters

This function takes only a single parameters −

• x − This is the floating point value.

Return Value

This function returns hyperbolic tangent of x.

Example 1

Following is the C library program to see the demonstration of tanh() function.

#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 above code produces the following result −

The hyperbolic tangent of 0.500000 is 0.462117 degrees

Example 2

In this program, the angle set to 30 degrees as an input. So, we can adjust the value of angle_degrees to explore different angles and observe their corresponding hyperbolic tangent values using tanh().

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

int main() {
    // angle in degree
    double angle_deg = 30.0; 

    // Convert degrees to radians
    double angle_radians = angle_deg * (M_PI / 180.0);

    // Calculate tanh
    double res = tanh(angle_radians);

    printf("tanh(%.2lf degrees) = %.4lf\n", angle_deg, res);
    return 0;
}

Output

On execution of above code, we get the following result −

tanh(30.00 degrees) = 0.4805

Example 3

Below the example decribe the approximation of e^x using tanh(). Here, we define the custom function my_exp() that use the formula identity e^x = 1 + tanh(x/2) / 1 - tanh(x/2) to return the result.

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

double my_exp(double x) {
    return (1.0 + tanh(x / 2.0)) * (1.0 - tanh(x / 2.0));
}

int main() {
    double x = 2.0; 

    double apx_exp = my_exp(x);

    printf("Approximate e^%.2lf = %.6lf\n", x, apx_exp);
    return 0;
}

Output

On execution of above code, we get the following result −

Approximate e^2.00 = 0.419974
Approximate e^2.00 = 0.419974