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Old 05-26-03, 04:06 AM   #86
StealthHawk
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Quote:
Originally posted by Behemoth
this is one way of shuffling instructions that manually reduces workload:

original program:

do a;
do b;
if (c == true) {do d;}
else { do e;}
do f;
do g;
do h;
do i;
do j;

do a;
if (c == true) {do d;}
else {do e;
do b;
do f;
do g;
do i;
do j;
}
do h;
Are these two things actually functionally and mathematically equivalent? Because they do not do the same thing. Although with your explantion they do have the same output. But to my understanding, have the same output DOES NOT make two things functionally or mathematically equivalent.

Here's what ATI said about their instruction shuffling:
1) it produces the same output as Futuremark's original code.
2) it is functionally equivalent to Futuremark's code.
3) it is mathematically equivalent to Futuremark's code.

To me, that implies that they are not skipping any steps.

What you are proposing is that they are putting a spin on the truth. If that is your opinion, then that is your opinion.

OR, are you actually saying that your code examples are both functionally and mathematically equivalent. If you are saying that, then please provide the basis for what definitions of functional equivalence and mathematical equivalence are.

I mean, for example, if you know the output of something is 4 you could caluclate it one of several ways.

1) 2+2 = 4
2) 2^2 = 4
3) cube root(64) = 4

The output of all 3 methods are the same, but I would not consider any of them to be functionally or mathematically equivalent. Maybe I don't know the definition.

edit: I would also like to throw this quesiton into the air. Suppose your definition of functionally and mathematically equivalent is correct, and that as long as output is always correct, there is equivalence.

You gave some examples of instructions that are bypassed, but because they do not effect the IQ, the output is still the same. That's all nice and good in hypotheticals, but are REAL shader programs like that? Can you really throw out instructions and have them not affect the resulting image?
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