Function: sum(sum(invert(gradient[2](tan(numbers("xyx") if numbers("xxr") > numbers('xry') else numbers('yxr')))), gradient[2](tan(numbers("xxr") if numbers('yxr') > numbers("xyx") else numbers('xry')))), invert(gradient[2](tan(numbers("xyx") if numbers('yxr') > numbers("xxr") else numbers('xry')))))
