Math Library Functions

02/12/15

Objective

• Use functions from the math.h library to do special calculations.

Side of Bandana Problem

I am manufacturing bandanas. Given the amount of cloth I can afford for each bandana, I want to know the measure of the side of that square. Write a program to find out the measure of the side of the square bandana.

Algorithm

1. Input a

2.

3. Output s

s=√a

Program

bandana.c

Built-in Functions• Call Syntax:

fname(arg1, arg2,… argn)• Example:

s = sqrt(area);• Include #include <math.h>• Must use -lm option when compiling

gcc -lm prog.c

Some Functions in cmath

sqrt(x)

arg - doubleresult - double

pow(x,y)

arg - doubleresult - double

fabs(x)

arg - doubleresult - double

√ x

x y

( x )

Some Functions in cmath

ceil(x) Rounds up arg - doubleresult - double

floor(x) Rounds down arg - doubleresult - double

Absolute Value of Integers

abs( ) arg - intresult - int

|x|

More Functions in cmath

log(x) Natural log of x arg - doubleresult - double

exp(x) e to the power x arg - doubleresult - double

•Examples

log(88.5) --> 4.483

exp(4.483) --> 88.5

Example

• Write a program to find the 4th root of a number input by the user.

• fourthRoot.c

Find Age Difference

Write a program to find the difference in age between two quarterbacks on a team.

Algorithm

1. Input qb1 and qb2

2. difference = |qb1 – qb2|

3. Output difference

Write the program today in lab. Started in qb.c