Re: Can't compile programs using functions in math.h

[bjorn rohde jensen <shamus at tdcadsl dot dk>]

Hi Martin,

 You need to link with the math library too, including the header is
not enough.

Try; gcc -o junk test.c -lm

Yours sincerely,

bjorn

Martin Rothberg wrote:
> 
> I am running redhat 7.2.  I can compile simple programs just fine, but I
> cannot compile programs the use functions such as sin or cos.  I need these
> as I am doing navigation calculations.  I have tried various things.  I
> confirmed that the compiler is finding math.h and the underlying
> mathcalls.h.  However, when I compile, I get:
> 
> [root@mercury root]# gcc -o junk test.c
> /tmp/ccINr3XY.o: In function `main':
> /tmp/ccINr3XY.o(.text+0x41): undefined reference to `cos'
> collect2: ld returned 1 exit status
> 
> I am not sure why it fails.  I have attempted to build both on command line
> and via KDevelop (in case I forgot to set up something).  Both yielded the
> same result.  I even reinstalled the RPM's for gcc in case I had damaged the
> install, but the result was the same.  Are there environment variables I
> need to explicitly set to use the standard C headers and libraries?  Since
> the header files are intact, am I missing the library itself?  Please advise
> 
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