I tried the program:

-------------------------------------
#include <math.h>

void main( void )
{
   double x1, x2, y;

   x1 = 1; x2 = 1;

   y = atan( x1 );
   y = atan2( x1,x2 );
}
---------------------------------------

And it compiled! But , before a got many times the
message :
>temp\31135(7) : error C2668: 'atan' : ambiguous call to
overloaded function

so be carefull about types. Never use atan(1), use
x = 1;
atan(x)

> so be carefull about types. Never use atan(1), use
> x = 1;
> atan(x)

....or u may just use atan((double)1)

>
> > so be carefull about types. Never use atan(1), use
> > x = 1;
> > atan(x)
>
> ....or u may just use atan((double)1)

I hope you can do something about it, I often forget that,
as it goes well in my local compiler, it's not reasonable
to use double(1), in sqrt and sin and cos function.

Is the ambiguilty caused by conversion both to double and
complex?