#math.h

How to: Why do you have to link the math library in C?

Why do you have to link the math library in C?

If I include <stdlib.h> or <stdio.h> in a C program I don’t have to link these when compiling but I do have to link to <math.h>, using -lm with gcc, for example:

gcc test.c -o test -lm

What is the reason for this? Why do I have to explicitly link the math library but not the other libraries?

Answer: Why do you have to link the math library in C?

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Today few math functions and constants available in Objective-C.

They are included in the math.h header. It's available into the iOS/OS X SDK.

MATH FUNCTIONS

pow(double, double) - power of

NSLog(@"%.f", pow(3,2) ); //result 9 NSLog(@"%.f", pow(3,3) ); //result 27

sqrt(double) - square root

NSLog(@"%.f", sqrt(16) ); //result 4 NSLog(@"%.f", sqrt(81) ); //result 9

ceil(double) - the next bigger integer

NSLog(@"res: %.f", ceil(3.000000000001)); //result 4 NSLog(@"res: %.f", ceil(3.00)); //result 3

floor(double) - removes the decimal part

NSLog(@"res: %.f", floor(3.000000000001)); //result 3 NSLog(@"res: %.f", floor(3.9999999)); //result 3

round(double) - rounds the argument

NSLog(@"res: %.f", round(3.5)); //result 4 NSLog(@"res: %.f", round(3.46)); //result 3 NSLog(@"res: %.f", round(-3.5)); //NB: this one returns -4

fmin(double, double) - the smaller

NSLog(@"res: %.f", fmin(5,10)); //result 5 NSLog(@"res: %.f", MIN(5,10)); //result 5

fmax(double, double) - the bigger

NSLog(@"res: %.f", fmax(5,10)); //result 10 NSLog(@"res: %.f", MAX(5,10)); //result 10

fabs(double) - the absolute value

NSLog(@"res: %.f", fabs(10)); //result 10 NSLog(@"res: %.f", fabs(-10)); //result 10 other functions to get the absolute value are described here

MATH CONSTANTS

Objetivos:

Praticar programação, reforçando a estrutura geral dos programas: entrada -> processamento (+memória) -> saída. 

Introduzir o uso das funções da biblioteca matemática. 

Aprender operadores aritméticos e a sua ordem de precedência. 

Atividades:

Revisão aula anterior

Implementação dos programas propostos.