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Mar
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Feb
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Jan
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Jan
3
comment Identify the independent variable in an expression
@Jens So you would advocate the approach in your answer to my question over the answers here in terms of generality?
Jan
3
comment Identify the independent variable in an expression
@Jens So I've been trying to figure out exactly why all the answers here are so different from the great answer you gave me to the question you referenced in your comment above.
Dec
26
accepted Compilation, square roots, and integers
Dec
26
comment Compilation, square roots, and integers
Thanks for the very detailed analysis. It clears things up for me quite a bit. One small comment: you say $MachineEpsilon == 2^-53; in fact it appears to be 2^-52.
Dec
25
comment Compilation, square roots, and integers
You are right about IntegerQ; I was just confused. But why should I start to see errors at $10^{14}$, which is over $45$ times smaller (over five bits) less than $2^{52}$? Again, my goal here is just to determine the range in which I can use this kind of integer function.
Dec
25
comment Compilation, square roots, and integers
But the problem is not with Sqrt, it's with ==: if you define isSq := IntegerQ@Sqrt@# &, that works properly with $2^{52}+1$ (that is, it returns False). Also, $2^{52}\approx 4\times 10^{15}$, which is much bigger than where I started to see failures of isSq2. So is there documentation anywhere of what tolerances == uses? (I don't really care what those tolerances are, but it would be nice to know in what range you could count on "exactness").
Dec
25
comment Fastest square number test
@KennyColnago You might want to look at this question that I posted this morning. I've done some more investigation of this issue.
Dec
25
revised Compilation, square roots, and integers
added 534 characters in body
Dec
25
comment Compilation, square roots, and integers
@JohnMcGee But doesn't isSq2 work with integers rather than reals?
Dec
25
asked Compilation, square roots, and integers
Dec
25
comment Selection bugs make Mathematica 10 unusable
No ideas, sorry. All seems pretty odd.
Dec
25
comment Selection bugs make Mathematica 10 unusable
I just noticed the length of time between your deleting the cache info and the bug reappearing. Certainly suggests crap building up somewhere. I'll keep this in mind.
Dec
25
comment Selection bugs make Mathematica 10 unusable
I see exactly what I expect; the cursor ends up between two appropriate characters, and nothing is selected.
Dec
25
comment Selection bugs make Mathematica 10 unusable
Well, up to you, obviously, but a) if you still have it on your machine it's easy to try, and b) if the bug does go away you have something definitive you can go back to Wolfram with.
Dec
25
comment Selection bugs make Mathematica 10 unusable
Have you tried dropping back to 9 to make sure the bug goes away?
Dec
25
comment Can we compile using only Integers Of Unusual Size?
Oh, and with respect to the minimum machine-size integer, I think you would expect it to be equal to -$MaxMachineInteger + 1, not -$MaxMachineInteger-1$. But in any case, -$MaxMachineInteger returning True is indeed unexpected.
Dec
25
comment Can we compile using only Integers Of Unusual Size?
Thanks. I didn't know about that package. And so given this (on my machine, this is $2^{63}-1$, as I expected), can I expect compiled programs with integer arguments to function properly up to this bound? (I realize that this is exactly what the documentation for Compile says.)