fbackelj

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14 years, 22 days

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These are answers submitted by fbackelj

Hello, I have found a difference in the handling of an integral between Maple versions 10 and 12. It bothers me since it was working in version 10, but now it gives a numeric exception... I'm not sure whether the replacement is valid or not, so I hope someone can validate it for me. Suppose I have the function definition > f := (x,a,b) -> int( t^(a-1) * (1-t)^(b-1), t=0..x ); As an example, consider > f(2.,3.,.4); This gives -0.8 both in Maple version 10 and 12. However, if I replace the previous statement with > f(x,a,b); > subs( x=2., a=3., b=4., % ); > evalf( % ); Then I still get -0.8 in Maple version 10, but in version 12 this results in "Error, (in GAMMA), numeric exception: division by zero"! The problem seems to be in the first line, f(x,a,b), which in Maple version 10 gives back the same/unchanged integral from the function definition. In Maple version 12 however, this integral is replaced with an expression involving GAMMA and hypergeom. (The error is generated since there is a factor of the form GAMMA(-b+1) which gives a pole for positive values of b.) I am wondering whether replacing this integral is valid, or whether this is a wrong replacement or even bug in Maple 12 (the same problem seems to appear in Maple version 11 as well). Many thanks for any reply. -- Regards, Franky.
I also find that Maple uses too many pages to print some simple things. It would be nice if you could change the zoom factor for the printout (like you can do on screen)... What I do currently, is set the page setup to A3. Then I print to a file (also selecting A3 as paper size, convert that to a pdf (or print it immediately to a pdf-printer, if possible), and then print that using e.g. acrobat on A4 paper, using its resize functionality. This saves a lot of pages when a lot of text/math is involved (i.e. no graphs)... Hope this works for you too! -- Regards, Franky
You are asking us to give you the solution for an assignment you got from your school (or university or whatever). Surely that could not be your intention... Normally you give us the code you have written so far, and then we may be able to assist you in correcting your procedure. Regards, Franky.
Yes, I was already experimenting with select, but in combination with depends instead of has... using has is a lot better, and seems to be exactly what I need. Thank you very much! P.s. I always find a way to get what I need, sooner or later, but frequently I discover afterwards that there's a much easier way to get the same result. Or maybe I'm just looking too far?! Regards, Franky
Surely, that was not my intention... my apologies. What I meant was: how can I retrieve the subexpression from expr that only involved (e.g.) z, where I only know that expr consists only of factors involving either m or z. That is, how can I extract the part involving z from (e.g.) the following expression: ((2*m+1)*(3*m+2)*z^2)/((2*m-1)*(1+z^2)*4) I know the expression can be written as the product of a(m) and f(z), but op can only be used if you know the order in which the factors of the expression are given... Regards, Franky
In one of my previous posts, I had a similar problem using type and assumptions simultaneously, see here. It seems that type does not use the assumptions. In your case, m is just a symbol, so it fails to check whether m>0 or not. If you would write this using is, then it would work in this case. That is, write > testp := proc(m) > if is( m = 0 ) then 0; > elif ( m > 0 ) then 1; > else -1; > end if; and you get the wanted results. Hope this helps, regards, Franky.
The Linux updates are only for the 32bit versions. For the 64bit versions, you must use the Unix update packages instead... Hope this helps. Regards, Franky.
I have given a presentation using Maple for a Mini-symposium on the Computation of Special Functions for ICNAAM 2005. You can see the result here. Well, this is only a print-version of the worksheet, but it gives you more or less an idea of how it looked on screen. I used sections and subsections and changed the styles (mostly fonts and spacing). I made sure that the contents fitted on a screen, and added enough space so that the next section didn't appear yet. I also added a "next section" link, so that you don't have to use the scrollbar on the right. This way, starting from the first screen, I just needed to click on the links and press enter for processing the maple commands. Off course, if you have lost of large output, it may clutter the screen, making it difficult to show what's important. So try to hide some details by using ':' or hiding the output. Hope this helps, Franky.
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