## maxima-bugs

 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-27 23:31:02 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Tracker Item Submitted) made by jensenripley You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-28 09:13:24 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by rswarbrick You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-28 09:15:02 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by rswarbrick You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-28 16:28:21 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by jensenripley You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-28 18:01:56 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by jcvtrip You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-30 17:27:44 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by jcvtrip You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-11-30 19:05:51 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0Comment By: Raymond Toy (rtoy) Date: 2011-11-30 11:05 Message: I have looked very briefly at this. The intermediate indefinite integrals look right, and maxima says the derivative simplifies to the integrand, so I don't really know what's wrong. I think the thing to do is to examine whether the indefinite integrals are actually correct. There could be a problem with choosing the wrong branch since one of the integrals involves inverse trig functions. ---------------------------------------------------------------------- Comment By: jcvtrip (jcvtrip) Date: 2011-11-30 09:27 Message: Please, some help on this question? Any comment would be helpful... ---------------------------------------------------------------------- Comment By: jcvtrip (jcvtrip) Date: 2011-11-28 10:01 Message: Hello, Here you have a transcript... Maxima version: 5.25.1 Maxima build date: 9:14 9/5/2011 Host type: i686-apple-darwin10.8.0 Lisp implementation type: SBCL Lisp implementation version: 1.0.47 expres:sqrt(4*x^2-y^2); (%o5) sqrt(4*x^2-y^2) integrate(integrate(expres, x,y,1),y,0,1); "Is "y-1" positive, negative, or zero?"n; "Is "y" positive or negative?"p; (%o6) (3*log(4*sqrt(3)+8)+4*%pi-1)/18 ev(%o6,numer); (%o12) 1.093118188249627 integrate(integrate(expres, y, 0,x),x,0,1); "Is "x" positive, negative, or zero?"p; (%o10) (2*%pi+3^(3/2))/18 ev(%o10,numer); (%o13) .6377409849936787 ---------------------------------------------------------------------- Comment By: Ripley (jensenripley) Date: 2011-11-28 08:28 Message: Thank you rswarbrick but you mistaked the input line ( % i3)... You wrote Integrate(integrate(expr, x,0, x), x,0,1) instead of Integrate(integrate(expr, y, 0, x) ,x ,0,1) ---------------------------------------------------------------------- Comment By: Rupert Swarbrick (rswarbrick) Date: 2011-11-28 01:15 Message: Drat. I didn't realise that sourceforge would eat the text formatting. If it isn't clear, the first time I get an answer with logs and sqrts. The second time, I get a more complicated integrate noun form. ---------------------------------------------------------------------- Comment By: Rupert Swarbrick (rswarbrick) Date: 2011-11-28 01:13 Message: With a recent version of the sources, I get the following: Maxima 5.25post http://maxima.sourceforge.net using Lisp SBCL 1.0.53.0.debian Distributed under the GNU Public License. See the file COPYING. Dedicated to the memory of William Schelter. The function bug_report() provides bug reporting information. (%i1) expr: sqrt(4*x^2-y^2); 2 2 (%o1) sqrt(4 x - y ) (%i2) integrate(integrate(expr, x, y, 1), y, 0, 1); Is y - 1 positive, negative, or zero? n; Is y positive or negative? pos; 3 log(4 sqrt(3) + 8) + 4 %pi - 1 (%o2) -------------------------------- 18 (%i3) integrate(integrate(expr, x, 0, x), x, 0, 1); Is x positive, negative, or zero? pos; Is y positive or negative? pos; rat: replaced -1.e-8 by -1/100000000 = -1.e-8 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-12-08 15:14:24 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by jensenripley You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0Comment By: Ripley (jensenripley) Date: 2011-12-08 07:14 Message: I couldn't realize that is simply a mistake... So, should I assume Maxima integrator subroutines aren't trustworthy? I like Maxima but it is not admissible for me to work with a not trusty "scientific" software... Could someone give a hand to have any reference to how Maxima manage integrals internally? I am going to do my best to find the bug... ---------------------------------------------------------------------- Comment By: Raymond Toy (rtoy) Date: 2011-11-30 11:05 Message: I have looked very briefly at this. The intermediate indefinite integrals look right, and maxima says the derivative simplifies to the integrand, so I don't really know what's wrong. I think the thing to do is to examine whether the indefinite integrals are actually correct. There could be a problem with choosing the wrong branch since one of the integrals involves inverse trig functions. ---------------------------------------------------------------------- Comment By: jcvtrip (jcvtrip) Date: 2011-11-30 09:27 Message: Please, some help on this question? Any comment would be helpful... ---------------------------------------------------------------------- Comment By: jcvtrip (jcvtrip) Date: 2011-11-28 10:01 Message: Hello, Here you have a transcript... Maxima version: 5.25.1 Maxima build date: 9:14 9/5/2011 Host type: i686-apple-darwin10.8.0 Lisp implementation type: SBCL Lisp implementation version: 1.0.47 expres:sqrt(4*x^2-y^2); (%o5) sqrt(4*x^2-y^2) integrate(integrate(expres, x,y,1),y,0,1); "Is "y-1" positive, negative, or zero?"n; "Is "y" positive or negative?"p; (%o6) (3*log(4*sqrt(3)+8)+4*%pi-1)/18 ev(%o6,numer); (%o12) 1.093118188249627 integrate(integrate(expres, y, 0,x),x,0,1); "Is "x" positive, negative, or zero?"p; (%o10) (2*%pi+3^(3/2))/18 ev(%o10,numer); (%o13) .6377409849936787 ---------------------------------------------------------------------- Comment By: Ripley (jensenripley) Date: 2011-11-28 08:28 Message: Thank you rswarbrick but you mistaked the input line ( % i3)... You wrote Integrate(integrate(expr, x,0, x), x,0,1) instead of Integrate(integrate(expr, y, 0, x) ,x ,0,1) ---------------------------------------------------------------------- Comment By: Rupert Swarbrick (rswarbrick) Date: 2011-11-28 01:15 Message: Drat. I didn't realise that sourceforge would eat the text formatting. If it isn't clear, the first time I get an answer with logs and sqrts. The second time, I get a more complicated integrate noun form. ---------------------------------------------------------------------- Comment By: Rupert Swarbrick (rswarbrick) Date: 2011-11-28 01:13 Message: With a recent version of the sources, I get the following: Maxima 5.25post http://maxima.sourceforge.net using Lisp SBCL 1.0.53.0.debian Distributed under the GNU Public License. See the file COPYING. Dedicated to the memory of William Schelter. The function bug_report() provides bug reporting information. (%i1) expr: sqrt(4*x^2-y^2); 2 2 (%o1) sqrt(4 x - y ) (%i2) integrate(integrate(expr, x, y, 1), y, 0, 1); Is y - 1 positive, negative, or zero? n; Is y positive or negative? pos; 3 log(4 sqrt(3) + 8) + 4 %pi - 1 (%o2) -------------------------------- 18 (%i3) integrate(integrate(expr, x, 0, x), x, 0, 1); Is x positive, negative, or zero? pos; Is y positive or negative? pos; rat: replaced -1.e-8 by -1/100000000 = -1.e-8 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3443554 ] Tío different results for an integral From: SourceForge.net - 2011-12-09 05:39:39 ```Bugs item #3443554, was opened at 2011-11-27 15:31 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ripley (jensenripley) Assigned to: Nobody/Anonymous (nobody) Summary: Tío different results for an integral Initial Comment: Hello, By integrating sqrt(4*x^2-y^2) into the triangle {0Comment By: Raymond Toy (rtoy) Date: 2011-12-08 21:39 Message: You should always check your work. Commercial systems have bugs too. The definite integration routines are in src/defint.lisp. References are included therein along with some description of the individual algorithms. If you're going to debug the code, you'll need to know lisp. If you can even find out that one of the definite or indefinite integrals is wrong would be a great help. Thanks for your help ---------------------------------------------------------------------- Comment By: Ripley (jensenripley) Date: 2011-12-08 07:14 Message: I couldn't realize that is simply a mistake... So, should I assume Maxima integrator subroutines aren't trustworthy? I like Maxima but it is not admissible for me to work with a not trusty "scientific" software... Could someone give a hand to have any reference to how Maxima manage integrals internally? I am going to do my best to find the bug... ---------------------------------------------------------------------- Comment By: Raymond Toy (rtoy) Date: 2011-11-30 11:05 Message: I have looked very briefly at this. The intermediate indefinite integrals look right, and maxima says the derivative simplifies to the integrand, so I don't really know what's wrong. I think the thing to do is to examine whether the indefinite integrals are actually correct. There could be a problem with choosing the wrong branch since one of the integrals involves inverse trig functions. ---------------------------------------------------------------------- Comment By: jcvtrip (jcvtrip) Date: 2011-11-30 09:27 Message: Please, some help on this question? Any comment would be helpful... ---------------------------------------------------------------------- Comment By: jcvtrip (jcvtrip) Date: 2011-11-28 10:01 Message: Hello, Here you have a transcript... Maxima version: 5.25.1 Maxima build date: 9:14 9/5/2011 Host type: i686-apple-darwin10.8.0 Lisp implementation type: SBCL Lisp implementation version: 1.0.47 expres:sqrt(4*x^2-y^2); (%o5) sqrt(4*x^2-y^2) integrate(integrate(expres, x,y,1),y,0,1); "Is "y-1" positive, negative, or zero?"n; "Is "y" positive or negative?"p; (%o6) (3*log(4*sqrt(3)+8)+4*%pi-1)/18 ev(%o6,numer); (%o12) 1.093118188249627 integrate(integrate(expres, y, 0,x),x,0,1); "Is "x" positive, negative, or zero?"p; (%o10) (2*%pi+3^(3/2))/18 ev(%o10,numer); (%o13) .6377409849936787 ---------------------------------------------------------------------- Comment By: Ripley (jensenripley) Date: 2011-11-28 08:28 Message: Thank you rswarbrick but you mistaked the input line ( % i3)... You wrote Integrate(integrate(expr, x,0, x), x,0,1) instead of Integrate(integrate(expr, y, 0, x) ,x ,0,1) ---------------------------------------------------------------------- Comment By: Rupert Swarbrick (rswarbrick) Date: 2011-11-28 01:15 Message: Drat. I didn't realise that sourceforge would eat the text formatting. If it isn't clear, the first time I get an answer with logs and sqrts. The second time, I get a more complicated integrate noun form. ---------------------------------------------------------------------- Comment By: Rupert Swarbrick (rswarbrick) Date: 2011-11-28 01:13 Message: With a recent version of the sources, I get the following: Maxima 5.25post http://maxima.sourceforge.net using Lisp SBCL 1.0.53.0.debian Distributed under the GNU Public License. See the file COPYING. Dedicated to the memory of William Schelter. The function bug_report() provides bug reporting information. (%i1) expr: sqrt(4*x^2-y^2); 2 2 (%o1) sqrt(4 x - y ) (%i2) integrate(integrate(expr, x, y, 1), y, 0, 1); Is y - 1 positive, negative, or zero? n; Is y positive or negative? pos; 3 log(4 sqrt(3) + 8) + 4 %pi - 1 (%o2) -------------------------------- 18 (%i3) integrate(integrate(expr, x, 0, x), x, 0, 1); Is x positive, negative, or zero? pos; Is y positive or negative? pos; rat: replaced -1.e-8 by -1/100000000 = -1.e-8 Is y positive or negative? pos; 1 / 2 2 2 2 [ y log(4 sqrt(4 x - y ) + 8 x) y log(4 %i y) (%o3) I (- ------------------------------- + -------------- ] 4 4 / 0 2 2 x sqrt(4 x - y ) + -----------------) dx 2 This, while unhelpful isn't wrong. Can you post a transcript of what you actually do and get (use maxima from the command line, maybe). Definitely include the version of Maxima that you're using. Rupert ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3443554&group_id=4933 ```