Absolute Value (abs) of NSDecimalNumber without loss of precision

Question

I need to get the absolute value of an NSDecimalNumber without loss of precision. I can\'t seem to find a way to do this without converting to decimal or float (with a loss

Answer 1

There is a minor error in the answer: negativeOne should be a pointer. Here is a revised answer:

- (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;
    }
}

And here is a version suitable to be used as a category on NSDecimalNumber:

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