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Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
Yes - I agree with @BlacKow. It won't work for x Log[a/b] + y Log[b/a] either...
Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
Sorry - of course. I misread what you had written as - Log[x^2]. If I had something of form Log[-x^2] I would want it left alone.
Jun
11
awarded  Commentator
Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
Cheers - I might have to do that I suppose. I'd thought of it, but hoped Mathematica had some more elegant way of dealing with it!
Jun
11
revised Simplifying Logs assuming arbitrary arguments real and positive
added 221 characters in body
Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
You simplification is exactly correct. It's just that I can't implement your strategy, because I don't actually know what will appear inside the Logs. It will involve some very complicated quantities in several variables coming from the expansion of hypergeometric functions. So I can't write an Assumption of z >0 because I don't know naively what form z will take! Maybe I could write Log[x_] > 0 as a pattern match assumption... I'll try that...
Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
Not really, because I have no idea what the argument of the Log is in general! If you know of a way of setting global assumptions on the argument of the Log function, that would certainly work. But I can't work out how to do this...
Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
Sure - have added these to the question.
Jun
11
revised Simplifying Logs assuming arbitrary arguments real and positive
added 423 characters in body
Jun
11
comment Simplifying Logs assuming arbitrary arguments real and positive
@MarcoB - thanks for the suggestion. As I understand it, PowerExpand will split the Logs up and I'll then have to reassemble them. In my case this would generate an enormous number of terms. I'd prefer to keep the vast majority of terms intact and just combine Logs when appropriate. Do you have a suggestion which would accomplish this?
Jun
11
asked Simplifying Logs assuming arbitrary arguments real and positive
Sep
24
awarded  Autobiographer
May
23
accepted How to simplify an expression into the sum of small fractions
May
23
comment How to simplify an expression into the sum of small fractions
The dots are dot products, as you would naturally expect. I did originally post Mathematica code, but I got downvoted so I thought the LaTeX was clearer. I will change it back when I have a moment.
May
23
comment How to simplify an expression into the sum of small fractions
Thank you - do you know why it doesn't just work directly with my variables?
May
23
comment How to simplify an expression into the sum of small fractions
Also could the downvoter explain how I can improve my post? I'm fairly active on other .SE sites, and as far as I'm aware it's poor etiquette to downvote without saying why!
May
23
awarded  Editor
May
23
comment How to simplify an expression into the sum of small fractions
I've added a simpler and clearer example, together with the expected simplification. Although this one is almost trivial to spot, it gets annoying in longer formulae!
May
23
revised How to simplify an expression into the sum of small fractions
Improved example
May
23
asked How to simplify an expression into the sum of small fractions