ICS 103: Computer Programming in C

Handout-05

Topic: Simple Standard Mathematical Library Functions

Instructor: M. Waheed Aslam.

Objective:

· To know about standard Mathematical library Functions and their use with examples.

Used to implement additional operators

· We learned how to form arithmetic expressions in C using some unary and binary operations

· However, with these operators alone we cannot write the full range of expressions that we can do in mathematics.

· For example, we do not know yet how to represent expressions like |a+b|, , in C language 

· To write such mathematical formulas and other mathematical functions like sin, cos, tan, square root, square, power, absolute value, etc., in C language, the library header file called math.h should be included in the beginning of the program along with the stdio.h file as follows:

#include <stdio.h>

#include <math.h>

· For sin, cos, tan the degrees should be converted into radians. To convert degrees to radians multiply the degrees with (22/7)/180 or (3.14/180) where 3.14 is the value of PI.

For example:

sin30⁰ is written as sin(30*3.14/180), a⁵ is written as pow(a, 5).

· To write the expression x = sin45⁰ + cos90⁰ + log₁₀6 + b⁴ in C language, we write:

x = sin(45*3.14/180) + cos(90*3.14/180) + log10(6) + pow(b,4)

The following Example Shows explanation and use of some important standard Math library Functions:

#include<stdio.h> // input output standard functions are defined in this

#include<math.h> // all standard math functions are defined

#include<stdlib.h> // here used only for rand() function

void main()

{int ab,random; // variable declarations

double cel,cosine,floatabs,flo,logbase_e,logbase_10,power,expo,sq_root;

ab=abs(-8); // gives absolute value of integer argument

cel=ceil(45.0001); // gives ceil value of double argument

cosine=cos(30*3.14159/180); //angle must be converted into radians first

expo=exp(1.0); // gives e to the power argument value

floatabs=fabs(-8.432); // gives absolute value of float argument

flo=floor(45.99356); // it truncates decimal digits

logbase_e=log(2.71828); //calculates natural log of argument (i.e base e)

logbase_10=log10(100); // calculates log of argument at base 10

power=pow(0.16,0.5); // calculates power i.e., pow(base, power) format

random=rand(); // generates random integer between 0 and the value

// associated with RAND_MAX, a constant macro defined in <stdlib.h>

sq_root=sqrt(2.25); // calculates square root of argument

printf("The absolute value of -8 is : %d\n", ab);

printf("The ceil value of 45.0001 is : %lf\n", cel);

printf("The cos value of degree 30 is : %lf\n", cosine);

printf("The exponential value of 1 is : %lf\n", expo);

printf("The absolute value of double type argument -8.432 is: %lf\n", floatabs);

printf("The floor value of 45.99356 is: %lf\n", flo);

printf("The natural log value of 2.71829 is: %lf\n", logbase_e);

printf("The log base 10 for value 100 is : %lf\n", logbase_10);

printf("The value of pow(0.16,0.5) is : %lf\n", power);

printf("A random integer between 0 and RAND_MAX is : %d\n", random);

printf("RAND_MAX = : %d\n", RAND_MAX);

printf("The value of sqrt(2.25) is : %lf\n", sq_root);

} // end of main

Output: Left as an exercise

Homework

Determine the value of the following C expression:

a) - (2 * (-3/(double) (4%10))) – (-6+4)

b) ceil(-7.2) * pow (4.0,2.0)