A better power function in C#?

Question

3.00/5 (2 votes)

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I am an engineer writing fairly mathematical code and sometimes the Math.Pow() function makes complex equations extremely difficult to read and debug.

As result I wrote the following simple code to override the ^ function, it sort of helps but the only probelm is that ^ has less priority than * for example. This means adding superfluous (in my view brackets in places where they shouldn't be needed).

Is there any better way to get a power function into C#?

C#

public struct MyDouble
    {
        double var;

        private MyDouble(double var)
        {
            this.var = var;
        }

        public static implicit operator MyDouble(double value)
        {
            return new MyDouble(value);
        }

         public static explicit operator double(MyDouble value)
         {
             return value.var;
         }

        public static MyDouble operator ^(MyDouble val1, MyDouble val2)
        {
            return new MyDouble(Math.Pow(val1.var, val2.var));
        }

        public static MyDouble operator *(MyDouble val1, MyDouble val2)
        {
            return new MyDouble(val1.var * val2.var);
        }

        public static MyDouble operator /(MyDouble val1, MyDouble val2)
        {
            return new MyDouble(val1.var / val2.var);
        }

        public static MyDouble operator +(MyDouble val1, MyDouble val2)
        {
            return new MyDouble(val1.var + val2.var);
        }

        public static MyDouble operator -(MyDouble val1, double val2)
        {
            return new MyDouble(val1.var - val2);
        }

        public static MyDouble operator -(MyDouble val1, MyDouble val2)
        {
            return new MyDouble(val1.var - val2.var);
        }

        public static MyDouble operator -(MyDouble val1)
        {
            return new MyDouble(-val1.var);
        }

        public static MyDouble operator -(double val1, MyDouble val2)
        {
            return new MyDouble(val1 - val2.var);
        }

        public static bool operator >(MyDouble val1, MyDouble val2)
        {
            return val1.var > val2.var;
        }

        public static bool operator <(MyDouble val1, MyDouble val2)
        {
            return val1.var < val2.var;
        }

        public static MyDouble operator ^(MyDouble val1, double val2)
        {
            return new MyDouble(Math.Pow(val1.var, val2));
        }
}

Posted 25-Jul-14 3:56am

manders999

Updated 25-Jul-14 3:57am

CHill60

v3

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Comments

CHill60 25-Jul-14 10:10am

In addition to Solution 1 - brackets used for clarification are never superfluous - based on questions I've seen on forums not everyone understands operator precedence well enough.

manders999 4-Aug-14 10:24am

Too many unnecessary brackets becomes a problem for readbaility, imagine a function with multiple embedded exponentials surrounded by up to a dozen brackets, its horrible.

5 solutions

Solution 1

You cannot change (or override) the evaluation precedence of operators in C#. Thus * will always take priority over ^ even if you were to overload them the other way round.

Is your gripe merely that Math.Pow is ugly?

Posted 25-Jul-14 4:01am

Rob Philpott

Solution 3

I want to give you a good practical advice: never override mathematical operators to make them denote mathematical functions. It only seems to you now that it would improve readability, but in fact it will later confuse even you. At the same time, it can be very convenient to override mathematical operator to denote something non-arithmetic. For example '+' can build a tree from two tree operands. Or add an element to a list. Or something else.

—SA

Posted 25-Jul-14 6:50am

Sergey Alexandrovich Kryukov

Comments

Andreas Gieriet 26-Jul-14 0:25am

My 5!
Cheers
Andi

Sergey Alexandrovich Kryukov 26-Jul-14 1:29am

Thank you, Andi.
—SA

Solution 4

If you really need to write mathematical expressions using a human friendly notation then you should code a mathematical expression parser.

Posted 25-Jul-14 10:17am

CPallini

v2

Solution 2

http://msdn.microsoft.com/en-us/library/aa691323(v=vs.71).aspx[^]

C# does not have a operator for exponentiation (so you can't override them to this purpose), you will have to either use Math.Pow() or create your own Power function
This link above will give you every C# operator in case of curiosity

^ is the Logical XOR. If you want to use it as Power, you will have to keep brackets)

Posted 25-Jul-14 4:09am

feeeh

Updated 25-Jul-14 4:11am

v2

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Andreas Gieriet · Accepted Answer · 2014-07-25T18:19:00

Solution 5

I understand that you are not happy with

C#

double a = ...;
double b = ...;
double c = Math.Pow(a,b);

How about

C#

...
double c = a.Pow(b);

If this is what you want, create an extension method for double type named Pow. E.g.

C#

public static class DoubleExtension
{
    public static double Pow(this double a, double b) { return Math.Pow(a, b); }
}

You may of course use other names than Pow for the extension method.
Cheers
Andi

Posted 25-Jul-14 18:19pm

Andreas Gieriet

Updated 25-Jul-14 18:27pm

v2

Comments

CHill60 26-Jul-14 9:15am

Good idea and very readable. 5'd

Andreas Gieriet 26-Jul-14 14:16pm

Thanks for your 5!
Cheers
Andi

manders999 4-Aug-14 10:25am

I like this idea, it seems to give the most readable solution, will give it a try.