Question

My iPhone has a line of code that looks like this:

double decimal2 = abs(newLocation.coordinate.longitude - degrees);

I’m trying to ensure that the value of decimal2 is always positive. However, decimal2 is currently -82.

Can anyone explain this? I’m not doing anything else to the value of decimal2.

Thanks.

Answer 1

would suggest you to use NSDecimalNumber

You could use the built-in functions of the NSDecimalNumber class to compare the number to zero, then multiply by -1 as appropriate. For example:

- (NSDecimalNumber *)abs:(NSDecimalNumber *)num {
    if [myNumber compare:[NSDecimalNumber zero]] == NSOrderedAscending) {
        // Number is negative. Multiply by -1
        NSDecimalNumber * negativeOne = [NSDecimalNumber decimalNumberWithMantissa:1
                                                                          exponent:0
                                                                        isNegative:YES];
        return [num decimalNumberByMultiplyingBy:negativeOne];
    } else {
        return num;
    }
}

in this case , there’s no loss of precision