Re: Math Weirdness

Robin Vickery schreef:

2008/7/15 tedd <tedd.sperling@gmail.com>:

I said: "Round-off errors normally don't enter into things unless your doing multiplication and division operations." And that is not "Bull" -- it's true. You can add and subtract all the floating point numbers (the one's we are talking about here) you want without any rounding errors whatsoever.

$ php -r 'echo 0.7 - 0.2 == 0.5 ? "true\n" : "false\n";' false The operation you do isn't important. You just can't represent certain numbers exactly in binary, just as you can't represent 1/3 exactly in decimal. They have to be rounded internally.

which makes php casting so much fun: $ php -r 'echo (string)(0.7 - 0.2) == 0.5 ? "true\n" : "false\n";' true

-robin