I m using 'log' function in C++, do I need a special lib?

case 9:


if (lb!=0)


{


lc = log(lb);


}


break;

I m using 'log' function in C++, do I need a special lib?
log


%26lt;math.h%26gt;





double log ( double x );





Calculate natural logarithm.


Returns the natural logarithm of parameter x.





Parameters.





x


Floating point value.





Return Value.


Logarithm of x.





Portability.


Defined in ANSI-C.


ANSI-C++ adds float and double overloaded versions of this function, with the same bahavior but being both, parameter and result, of one of these types.





Example.





/* log example */


#include %26lt;stdio.h%26gt;


#include %26lt;math.h%26gt;





int main ()


{


double param, result;


param = 5.5;


result = log (param);


printf ("ln(%lf) = %lf\n", param, result );


return 0;


}





Output:


ln(5.500000) = 1.704748
Reply:yes, include the line below in your source code:


#include%26lt;math.h%26gt;
Reply:You code module needs to #include %26lt;math.h%26gt; to get the function prototype for the log function. You will also need to ensure the compiled object module is linked with the math library (libm.a). In a UNIX environment put a -lm argument on the linker command.