tanh

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

int main(void)
{
  double val = -1.0;

  do {
    printf("Hyperbolic tangent of %f is %f.\n", val, tanh(val));
    val += 0.1;
  } while(val<=1.0);

  return 0;
}

output

Hyperbolic tangent of -1.000000 is -0.761594.
Hyperbolic tangent of -0.900000 is -0.716298.
Hyperbolic tangent of -0.800000 is -0.664037.
Hyperbolic tangent of -0.700000 is -0.604368.
Hyperbolic tangent of -0.600000 is -0.537050.
Hyperbolic tangent of -0.500000 is -0.462117.
Hyperbolic tangent of -0.400000 is -0.379949.
Hyperbolic tangent of -0.300000 is -0.291313.
Hyperbolic tangent of -0.200000 is -0.197375.
Hyperbolic tangent of -0.100000 is -0.099668.
Hyperbolic tangent of 0.000000 is 0.000000.
Hyperbolic tangent of 0.100000 is 0.099668.
Hyperbolic tangent of 0.200000 is 0.197375.
Hyperbolic tangent of 0.300000 is 0.291313.
Hyperbolic tangent of 0.400000 is 0.379949.
Hyperbolic tangent of 0.500000 is 0.462117.
Hyperbolic tangent of 0.600000 is 0.537050.
Hyperbolic tangent of 0.700000 is 0.604368.
Hyperbolic tangent of 0.800000 is 0.664037.
Hyperbolic tangent of 0.900000 is 0.716298.
Hyperbolic tangent of 1.000000 is 0.761594.