On Mon, Jun 18, 2012 at 10:21:34AM -0700, Ben Pfaff wrote: > Bruno Haible <br...@clisp.org> writes: > > > In theory you would be right that data should be validated at the boundaries > > of the program, that is, when they are read from outside sources. But no > > program I know of does this for unconstrained floating-point numbers. > > That's an interesting point. GNU PSPP reads unconstrained > "double"s from SPSS data files without validating them[*], since
This is not a problem. As long as you're assuming IEEE, all 64-bit patterns are valid long double values. The issue only occurs for long double, a type that's very different in both arithmetic properties and representation between systems. On typical systems, it has padding bits (which might or might not be required to be all-zero) as well as bit combinations that are completely invalid. > it never occurred to me that this was a bad idea. A function to > validate a floating-point number would therefore be useful in > PSPP. It's only as useful as long doubles, which is, well, not very useful to most people. Rich
