In general, any mathematical expression accepted by C, FORTRAN,
Pascal, or BASIC is valid.  The precedence of these operators is
determined by the specifications of the C programming language.
White space (spaces and tabs) is ignored inside expressions. 

Complex constants may be expressed as the {real,imag}, where <real>
and <imag> must be numerical constants.  For example {3,2}
represents 3 + 2i; {0,1} represents 'i' itself. 
