Question

What is the most recommended data type to use in scientific calculation in .Net? Is it float, double or something else?

Answer 1

Scientific values tend to be “natural” values (length, mass, time etc) where there’s a natural degree of imprecision to start with – but where you may well want very, very large or very, very small numbers. For these values, double is generally a good idea. It’s fast (with hardware support almost everywhere), scales up and down to huge/tiny values, and generally works fine if you’re not concerned with exact decimal values.

decimal is a good type for “artificial” numbers where there’s an exact value, almost always represented naturally as a decimal – the canonical example for this is currency. However, it’s twice as expensive as double in terms of storage (8 bytes per value instead of 4), has a smaller range (due to a more limited exponent range) and is significantly slower due to a lack of hardware support.

I’d personally only use float if storage was an issue – it’s amazing how quickly the inaccuracies can build up when you only have around 7 significant decimal places.

Ultimately, as the comment from “bears will eat you” suggests, it depends on what values you’re talking about – and of course what you plan to do with them. Without any further information I suspect that double is a good starting point – but you should really make the decision based on the individual situation.