On 12/26/2011 7:59 AM, Vincent Lefevre wrote:
On 2011-12-26 12:37:27 +0100, David Brown wrote:
If it matters that "a + b - c" be calculated "(a + b) - c" or "a + (b - c)",
then use brackets.
but brackets shouldn't change anything with -fassociative-math.
In C, brackets are purely syntactic, i.e. a + b - c is equivalent
to (a + b) - c.
This was so prior to 1989, but the rules changed with the advent of ISO
standards. Even where compilers support algebraic simplification across
parentheses in violation of the standards, the results are unreliable as
well as non-portable.
--
Tim Prince
