atan method
Implementation
MathComplex atan(){
if( _im == 0.0 ){
return floatToComplex( fatan( _re ) );
}
MathComplex d = MathComplex( -_re, 1.0 - _im );
if( d.equal( 0.0 ) ){
ClipMath.setComplexError();
}
// i * log( (i + this) / d ) * 0.5
MathComplex i = MathComplex( 0.0, 1.0 );
MathComplex c = i.mul( i.add( this ).div( d ).log() ).mul( 0.5 );
c._re = _radToAng( c._re );
c._im = _radToAng( c._im );
return c;
}