undefined reference to 'sqrt'

Help! Where is the mistake ?

Code:

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double x = 0.0 , y = 0.0, r = x*x + y*y;
...
printf("\n%i        %.2f        %.2f        %.2f\n",i,x,y,sqrt(r));
...ore sqrt(x*x + y*y));

---

The compiler tell me things like this:
gmake[2]: *** [c_teilchen_in_kasten] Fehler 1
gmake[2]: Das Target »all« wurde wegen Fehlern nicht aktualisiert.
/home/joerg/c_teilchen_in_kasten/src/c_teilchen_in_kasten.c:82: undefined reference to `sqrt'

Thanks for life out there !

you have to link to the math library.
add -lm to the linker flags.
Kurt

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define N 5

I did !

No. That's just including the math header.
I don't know what gmake is or what kind of ide you're using. this -lm flag has to be added either to your projects linker options or to your projects makefile.
Kurt

I'm using Kdevelop under suse linux 10.2

Quote:

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Originally Posted by joerg

I'm using Kdevelop under suse linux 10.2

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Guess you have to wait some time. Have just started to install kdevelop. Maybe sombody else can help in the meantime.
Kurt

Sorry but it will take a few month until I understand kdevelops project management.
you could try to compile from the commandline in the meantime
e.g.

Code:

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gcc c_teilchen_in_kasten.c -lm

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Kurt

Quote:

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Originally Posted by joerg

I'm using Kdevelop under suse linux 10.2

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So? You'll have to tell kdev that you WANT the math lib (-lm).

Thank you Kurt !

It's a mess.
you wright a couple of words for source code, therefore you have to go through a jungle of s...
and Kdelvelop creates an entire PROJEKT !

Joerg

For simple projects, certainly those in a single file, compiling from the command line is easiest.
Plus you get to learn about all the things like include and library paths etc.