Engineering notation in C#?

Question

Is there any code out there (or a built-in function) which allows outputting a floating point number in engineering notation?

For example, 1.5e-4 would

Answer 1

Rather than subclassing, I'd take advantage of the fact that Double implements IFormattable and write an IFormatProvider that formats the number. Then I'd have code that looks similar to:

double d = 123.45;
Console.WriteLine(d.ToString(null, new MyCustomFormat()));