Re: Some bugs in Mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg59713] Re: Some bugs in Mathematica
- From: Bill Rowe <readnewsciv at earthlink.net>
- Date: Thu, 18 Aug 2005 00:17:05 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
On 8/17/05 at 4:00 AM, akhmel at hotmail.com (Alex) wrote: >Bill Rowe wrote: >>Your "logic" doesn't follow. If you agree with the point I was >>making, then you must realize two different programmers are likely to >>include different transformssimply because of differences design >>considerations or programming style. That is, not including a >>specific transform is not evidence of sloppy >programming. >Those are general phrases, which actually mean nothing. The issue >is Mathematica couldn't compute a very elementary integral. There >is no excuse for that. Mathematica did compute the integral. The fact the result wasn't in a form to your liking doesn't change this. >>I believe that to be an unreasonable expectation. >It's more than reasonable. There are not that many substitutions. I >can name 3 or 4. Can you name 125? The actual number of substitutions is only one of several factors than will affect execution time. My comment dealt with an expression of arbitrary complexity. It is quite easy to replace one or more variables in you integrand with a sum of say four or five terms, expand the result to get something that is not easily reconizable as equivalent. Your original comment implied you expect Mathematica to try every possible grouping of variables in such an expression to find the simple transformation. This is not a reasonable expectation for expressions of arbitrary complexity. >>And your basis for this assertion is ....? >I addressed it before, the substitutions are simple and the number >of different substitutions is very limited. I tried several >substitutions myself and got result of simplification practically >immediately. And my computer is 5 years old, so it is not fast at >all. Can you imagine how a fast computer would behave? Again, my comment was for an expression of arbitrary complexity. Your comments here do not address the point. >>How is "appearance" of an integrad to be defined for a system like >>Mathematica? I am confident algorithm needed to define "appearance" >>will lead >to unacceptable performance if every possible grouping of >>variables in an arbritrary complex expression is considered. >You cannot have it both ways: you claim that Mathematica has a >table of integrals, it means that they have managed to write a >table in computer-readable and computer-searchable form. And now >you are telling me that this just cannot be done! Now, which one is >right? You are conflating to separate things. One is the existence of an integral table, The other is the ability to transform an expression into a form that matches one of the forms tabulated. Simply because a table exists doesn't mean you can transform a complex expression into a form for which the table can be used. >>I agree there is a vast difference between "not perfect" and >>"inadequate". I strongly disagree that Mathematica is "inadequate". >>If Mathematica is >inadequate for your needs, you are certainly free >>to use some other software. >Please give me your definition of inedequate. Would you for example >call a system inadequate when it cannot integrate a rational >expression? Would you call it inadequate when it cannot integrate x >dx? How far would you go? Where do you draw the line? I draw the >line in undergraduate calculus. Am I wrong? Again, Mathematica computed an answer. It just wasn't in the form you wanted. >You wrote a lot of things, which proves absolutely nothing, instead >of honestly admitting that this is Mathematica's fault, which needs >to be corrected. I don't agree with you there is a problem that needs fixing here. Mathematica got a result. You can get Mathematica to give you a result in a different form by formulating the input differently. The only issue seems to be you don't like the form of the result you got. >I noticed that you published over 100 postings, each of them can be >summarized as follows: "Mathematica is right. Even when Mathematica >is wrong, it is still right to be wrong". Why is this so? I haven't counted the number of postings I've made. But I am certain many of them have been answers to specific problems posted by others which can not be characterized as you suggest above. >Kozlowski published over 1000 postings; all of them are of the same >kind. Have any of you ever encountered Mathematica having a bug, >Mathematica being inedequate in certain sense? Never? Yes, I've encountered problems with Mathematica. When I do encounter things where Mathematic is clearly wrong, I report them to Wolfram. Eventually, they seem to get corrected but not always as soon as I might like. In the meantime, I look for a different approach to whatever I am trying to solve. Forunately, Mathematica has a very rich set of tools that allow more than one approach to solvng a specific problem. Usually, that is sufficient for me to get the result I need. >Both you and Kozlowski are trying to make user feel inedequate, >"blind", stupid, etc. It doesn't look good. It doesn't look good at >all. I can't speak for Andrzej, but as for myself my motivation for posting isn't as you suggest above. -- To reply via email subtract one hundred and four
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