sqrt() function help

[willc0de4food]

hey, i'm curious as to how you would go about passing a variable to the sqrt() function to get the square root of it. i've found that you can directly input a number to it, but when i try something like:

square_root = sqrt(user_number);

i get:
[tim@shibby documents]$ gcc -o SqRt sqrt.c
/tmp/ccuCIkhZ.o(.text+0x82): In function `main':
: undefined reference to `sqrt'
collect2: ld returned 1 exit status

so how can i do this? is there a better way? thanks

[Maragato]

hey, i'm curious as to how you would go about passing a variable to the sqrt() function to get the square root of it. i've found that you can directly input a number to it, but when i try something like:

square_root = sqrt(user_number);

i get:
[tim@shibby documents]$ gcc -o SqRt sqrt.c
/tmp/ccuCIkhZ.o(.text+0x82): In function `main':
: undefined reference to `sqrt'
collect2: ld returned 1 exit status

so how can i do this? is there a better way? thanks

Oki as I dont have your full code I will try to figure out what is wrong. Are you incluiding the #<math.h> header?

[MadCow257]

Without the full code I can't know, but I belive that error would most likely come from the lack of the math.h header.
Add
#include <math.h>
to the top of your code if you don't have it already

[chrismiceli]

You have to link with the math library.
gcc -o blah blah.c -lm

[willc0de4food]

yea, i included the math.h header and i also tried including the tgmath.h header b/c i was unsure about which one to include and neither worked.

but chrismiceli adding -lm worked thanks. but can you tell me what that does?

[Maragato]

yea, i included the math.h header and i also tried including the tgmath.h header b/c i was unsure about which one to include and neither worked.

but chrismiceli adding -lm worked thanks. but can you tell me what that does?

It is linking the library, take a look here -> http://developer.apple.com/documenta...libtool_3.html
maybe no the best site for the topic but surely explains what you need.