Activity for David Billinghurst
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David Billinghurst committed [ad2082] on Code
cobyla.texi.m4: Add hyperlinks and DOI to references. Hyperlink maxima files.
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Remove stray comment string from colnew example 5
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> No problem. Please follow up on the maxima-discuss list. On 2/09/2025 18:04, David J. López via Maxima-bugs wrote: <meta http-equiv="content-type" content="text/html; charset=UTF-8"> Thank you for your quick and detailed answers, and for the article as well. Apologies for opening this ticket as a bug. [bugs:#4604] Floating point errors Status: not-a-bug Group: None Created: Mon Sep 01, 2025 08:07 AM UTC by David J. López Last Updated:...
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Floating point errors
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This is not a bug. It is the expected behavior of floating point arithmetic on any computer. maxima has a number of ways to address the issue you have reported. I suggest you ask specific questions on the Maxima discussion list You can refer to What every computer scientist should know about floating-point arithmetic for some background.
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Fix malformed hyperlinks in "Examples for colnew"
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I just tried on cygwin/clisp/windows11 with 5.47.0 and git head. Same results as Robert. (%i2) build_info(); (%o2) Maxima-version: "5.47.0" Maxima build date: "2023-06-25 17:16:51" Host type: "x86_64-pc-cygwin" Lisp implementation type: "CLISP" Lisp implementation version: "2.49+ (2010-07-17) (built on Walter [192.168.178.24])" User dir: "/home/dabilling/.maxima" Temp dir: "/tmp" Object dir: "/home/dabilling/.maxima/binary/5_47_0/clisp/2_49___2010_07_17___built_on_Walter__192_168_178_24__" Frontend:...
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archive/configure is error by ubuntu20.04
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I will close this as not-a-bug. If you still have problems ask on the maxima-discuss mailing list https://sourceforge.net/p/maxima/mailman/
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Ignore everything in archive/. archive/configure dates from 2000-12-09 Follow the build instructions in INSTALL. Specifically try the "UNIX GNU AUTOTOOLS BUILD AND INSTALL" recipe cd to root of maxima source tree sh bootstrap ./configure make make check make install You will need a number of prerequisites installed to build the documentation, including recent texinfo and latex.
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I will do this today. I am already making some small changes to the minpack documentation.
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I will add a References section to the minpack section of the manual.
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Corretly sort entry for bug #4355
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Add A&S and DLMF links to Package contrib_ode documentation.
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The function `antid` is listed in the category for derivatives
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This is fixed in git master. Don't know when.
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[bugs:#4355] documentation for trigvalue etc
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documentation for trigvalue etc. should mention load(trigtools)
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Fixed. There is, of course, more that could be done. Commit [e526957d0]
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[bugs:#4355] documentation for trigvalue etc
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[bugs:#4355] documentation for trigvalue etc
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Add note that trigeval is preferred over trigvalue. Mention trigtools in the section Introduction to Trigonometric. Commits [e73da8f77] and [1d1373cb4]
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Partially addressed with Commit: [9c531d]
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[bugs:#4355] documentation for trigvalue etc
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I added an example of this to the algsys documentation as 20.2.3 Example 2: Equations with irrational coefficients. Not much of a solution.
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Trivial changes to documentation for Package Levin.
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Annotate references for Package Levin.
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Extend Example 1 for levin package documentation.
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Rework Example 1 for Levin transforms so that update_examples script works.
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Document contrib/share/levin package
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problem with calculation of eigenvalues/eigenvectors
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Need to improve the documentation to link between eigenvalue() and LAPACK routines. I thought we had done that.
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Pavel, The eigenvalue() and eigenvector() functions in maxima solve the characteristic equation symbolically. Even a 4x4 matrix is a challenge. I can expand on this if you are interested. For floating-point inputs use the dgeev() function from the lapack package. The manual has examples.
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Modified Bessel differential equation
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Feature added with commit [106905]
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ode2 now solves Modified Bessel differential equations.
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Add routine to solve Modified Bessel differential equation to ode2.
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Arfken, Weber and Harris, Mathematical Methods for Physicists 7th ed (2012) Section 14.5 covers the modified Bessel equation pretty well. I see the last line of function modifiedbessel2 should be return(y = %k1*bessel_i(nu,x-pt) + %k2*bessel_i(-nu,x-pt))))$ This is closer to the bessel2 function and eliminates the issue with ode_check - probably because it is correct. I will commit this in a day or two.
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The last line of function modifiedbessel2 should read return(y = %k1*bessel_i(nu,x-pt) + %k2*bessel_k(nu,x-pt))))$ Case n=3/2 now works. It isn't simplified to zero by ode_check, but the result simplifies to zero numerically. This ode_check issue is [bug:#4392] (%i32) eq:mbde,n=3/2; (%o32) x^2*'diff(y,x,2)+x*'diff(y,x,1)+(-x^2-9/4)*y = 0 (%i33) s:ode2(eq,y,x); (%o33) y = bessel_k(3/2,x)*%k2+bessel_i(3/2,x)*%k1 (%i34) [method,r:ode_check(eq,s)]; (%o34) [modifiedbessel, (bessel_k(7/2,x)*%k2*x^2)/4-(bessel_k(3/2,x)*%k2*x^2)/2...
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The last line of function modifiedbessel2 should read return(y = %k1*bessel_i(nu,x-pt) + %k2*bessel_k(nu,x-pt))))$ Case n=3/2 now works. It isn't simplified to zero by ode_check, but the result simplifies to zero numerically. This ode_check issue is [bug:4392] (%i32) eq:mbde,n=3/2; (%o32) x^2*'diff(y,x,2)+x*'diff(y,x,1)+(-x^2-9/4)*y = 0 (%i33) s:ode2(eq,y,x); (%o33) y = bessel_k(3/2,x)*%k2+bessel_i(3/2,x)*%k1 (%i34) [method,r:ode_check(eq,s)]; (%o34) [modifiedbessel, (bessel_k(7/2,x)*%k2*x^2)/4-(bessel_k(3/2,x)*%k2*x^2)/2...
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bessel_simplify failure with modified Bessel function expression
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Modified Bessel differential equation
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The last line of function modifiedbessel2 should read return(y = %k1*bessel_i(nu,x-pt) + %k2*bessel_k(nu,x-pt))))$ Case n=3/2 now works. It isn't simplified to zero by ode_check, but the result simplifies to zero numerically. (%i32) eq:mbde,n=3/2; (%o32) x^2*'diff(y,x,2)+x*'diff(y,x,1)+(-x^2-9/4)*y = 0 (%i33) s:ode2(eq,y,x); (%o33) y = bessel_k(3/2,x)*%k2+bessel_i(3/2,x)*%k1 (%i34) [method,r:ode_check(eq,s)]; (%o34) [modifiedbessel, (bessel_k(7/2,x)*%k2*x^2)/4-(bessel_k(3/2,x)*%k2*x^2)/2 +(bessel_k(1/2,x)*%k2*x^2)/4...
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Ah. I forgot I could add attachments. Edit. ode2.mac updated with one-line patch below.
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Ah. I forgot I could add attachments.
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Here is an initial implementation. Works for simple cases, but not for n=3/2. Enough for tonight. Here is a patch to ode2.mac. Introduce new function modifiedbessel2.mac and call it. Evert: I can send you a complete patched ode2.mac if you aren't familiar with the patch utility. $ diff -c /usr/local/src/maxima/share/diffequations/ode2.mac ode2.mac *** /usr/local/src/maxima/share/diffequations/ode2.mac Mon Sep 12 21:21:58 2016 --- ode2.mac Tue Oct 22 21:54:59 2024 *************** *** 11,17 **** declare_translated(boundtest,noteqn,nlxy,nly,nlx,xcc2,bessel2,euler2,...
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Modified Bessel differential equation
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This looks "trivial" to implement: clone the function bessel2, flip a couple of signs, change the Bessel function names, call the new function and fix the testsuite. I may have time to investigate later this week.
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The function of interest is maxima code - the nine-line function bessel2 in file share/diffequations/ode2.mac.
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I don't understand why solveradcan:true returns implicit solutions. This isn't mentioned in the manual. Given the effect of solverradcan:true the effect of solveexplicit:true inhibiting implicit solutions is as documented, Maxima 5.47.0 https://maxima.sourceforge.io using Lisp CLISP 2.49+ (2010-07-17) 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) display2d:false$ (%i2)...
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Update solution for ODE Murphy 1.34
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Fixed with commit [1be377]
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Add assumptions for tests Kamke 2.3 and 2.4
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Maxima can't differentiate beta function
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Fixed with commit [1be3779a]
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Bug #4325: Maxima can't differentiate beta function
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The following works. I am not familiar with MQAPPLY and would welcome guidance on style. ;; Derivative of beta function ;; https://functions.wolfram.com/GammaBetaErf/Beta/ ;; https://en.wikipedia.org/wiki/Beta_function (defprop %beta ((a b) ; derivative wrt a ((mtimes) (($beta) a b) ((mplus) ((mqapply) (($psi array) 0) a) ((mtimes) -1 ((mqapply) (($psi array) 0) ((mplus) a b))))) ; derivative wrt b ((mtimes) (($beta) a b) ((mplus) ((mqapply) (($psi) 0) b) ((mtimes) -1 ((mqapply) (($psi array) 0)...
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See the thread https://sourceforge.net/p/maxima/mailman/maxima-discuss/thread/CAMTHLKj1zk9G8H%3Dfpqi5Mx63jfXt4tH7FSHXQsvM7ubNCh1h1Q%40mail.gmail.com/#msg58730878 In particular https://sourceforge.net/p/maxima/mailman/message/58731017/ where Stavros says domain:real/complex sounds like a really powerful global setting -- am I working in the reals or in the complex numbers? But in fact, it has a very narrow meaning -- it (together with m1pbranch and radexpand) simply controls the simplification of...
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Three solutions are returned when domain:complex . (%i1) display2d:false$ (%i2) eq1:x^3+x^2-x+%pi-1$ (%i3) domain:complex$ (%i4) algsys([eq1],[x]); (%o4) [[x = (4*(54/(9*sqrt((27*%pi^2-32*%pi)/3)-27*%pi+16))^(1/3) +9*((9*sqrt((27*%pi^2-32*%pi)/3)-27*%pi+16)/54)^(1/3)-3) /9], [x = -((4*(-(54/(9*sqrt((27*%pi^2-32*%pi)/3)-27*%pi+16)))^(1/3) +9*(-((9*sqrt((27*%pi^2-32*%pi)/3)-27*%pi+16)/54))^(1/3)+3) /9)], [x = ((4*sqrt(3)*%i-4)*(54/(9*sqrt((27*%pi^2-32*%pi)/3)-27*%pi+16)) ^(1/3) +(-(3^(5/2)*%i)-9)*((9*sqrt((27*%pi^2-32*%pi)/3)-27*%pi+16)/54)...
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sqrtdenest cannot denest sqrt(sqrt(3)*%i-1))
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rectform can do this if domain:complex. That will do for now. (%i1) display2d:false$ (%i2) eq1:sqrt(sqrt(3)*%i-1)$ (%i3) domain:complex$ (%i4) rectform(eq1); (%o4) (sqrt(3)*%i)/sqrt(2)+1/sqrt(2)
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raddenest improper argument
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raddenest - in git HEAD of 2024-01-22 - gets this wrong. This would be unacceptable for algsys/solve. (%i1) load("raddenest")$ (%i2) eq1:sqrt(sqrt(3)*%i-1)$ (%i3) sqrtdenest(eq1); (%o3) sqrt(sqrt(3) %i - 1) (%i4) eq2:raddenest(eq1); 1 sqrt(6) (%o4) ─────── - ─────── sqrt(2) 2 (%i5) rectform(float(eq1)); (%o5) 1.224744871391589 %i + 0.7071067811865476 (%i6) rectform(float(eq2)); (%o6) - 0.5176380902050415 Reported as bug [#4256] as fix is independent.
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raddenest failure with sqrt(sqrt(3)*%i-1)
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The sqrtdenest enhancement is now bug [#4255]. It is worthwhile enhancement independently of this
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sqrtdenest cannot denest sqrt(sqrt(3)*%i-1))
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sqrtdenest cannot denest sqrt(sqrt(3)*%i-1))
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I haven't found too many references to denesting complex expressions . There is https://brownmath.com/alge/nestrad.htm
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After removing the call to $rectform from SIMPLIFY-AFTER-SUBST algsys returns three solutions. (%i9) eq1:x^3+x^2-x+%pi-1$ (%i10) sa:algsys([eq1],[x]); (%o10) [[x = -((2^(2/3)*(3^(9/2)*sqrt(27*%pi^2-32*%pi)+729*%pi-432)^(1/3) -3*2^(2/3)*(3^(3/2)*sqrt(27*%pi^2-32*%pi)-27*%pi+16)^(1/3)+6) /18)], [x = ((2^(2/3)*sqrt(3)*%i+2^(2/3)) *(3^(9/2)*sqrt(27*%pi^2-32*%pi)+729*%pi-432)^(1/3) +(2^(2/3)*3^(3/2)*%i-3*2^(2/3)) *(3^(3/2)*sqrt(27*%pi^2-32*%pi)-27*%pi+16)^(1/3)-12) /36], [x = -(((2^(2/3)*sqrt(3)*%i-2^(2/3))...
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simplify-after-subst tries two approaches 1) ratsimp 2) if $constantp(e) sqrtdenest + rectform + rootscontract + ratsimp then takes smallest expression rectform is causing problems. p1 and p2 are expressions from above (%i2) display2d:false$ (%i3) p1:((sqrt(3)*%i)/2-1/2)*((sqrt(%pi)*sqrt(27*%pi-32))/(2*3^(3/2)) +(-(3*(%pi-1))-1)/6+(-1)/27) ^(1/3)$ (%i4) rectform(float(p1)); (%o4) 0.16342849479571833-0.28306645639069*%i (%i5) r1:rectform(p1); (%o5) -(-((sqrt(%pi)*sqrt(27*%pi-32))/(2*3^(3/2)))-(-(3*(%pi-1))-1)/6+1/27)^(1...
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Picking apart the solution finds two subexpressions with the same problem. Expressions p1 and p2 below have different floating point values after processing with lisp function simplify-after-subst (%i2) display2d:false$ (%i3) s2:((sqrt(3)*%i)/2+(-1)/2)*((sqrt(%pi)*sqrt(27*%pi-32))/(2*3^(3/2)) +(-(3*(%pi-1))-1)/6+(-1)/27) ^(1/3) +(4*(-1/2-(sqrt(3)*%i)/2))/(9*((sqrt(%pi)*sqrt(27*%pi-32)) /(2*3^(3/2)) +(-(3*(%pi-1))-1)/6+(-1)/27) ^(1/3))+(-1)/3$ /* Here is the problem. simplify\-after\-subst changes...
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Looks similar to bug [#4163]
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raddenest failure
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OK. The issue is with the second solution found by solve. (%i1) display2d:false$ (%i2) expr:((sqrt(3)*%i)/2+(-1)/2)*((sqrt(%pi)*sqrt(27*%pi-32))/(2*3^(3/2)) +(-(3*(%pi-1))-1)/6+(-1)/27) ^(1/3) +(4*(-1/2-(sqrt(3)*%i)/2))/(9*((sqrt(%pi)*sqrt(27*%pi-32))/(2*3^(3/2)) +(-(3*(%pi-1))-1)/6+(-1)/27) ^(1/3))+(-1)/3$ (%i3) rectform(float(expr)); (%o3) 0.8945133161601935*%i+0.5099711601368959 The lisp simplifying function within algsys simplify-after-subst converts this to the third solution found by solve....
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Add "Examples for algsys" section to "Equations" chapter of manual.
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Correct trivial typo
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Correct anchor for reference (Gawain&Ball 1978)
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Fix itemized list in "References for colnew"
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Regenerate examples
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Correct comment in code for colnew Example 2: Deformation of a spherical cap
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Renable test for bug #1106 that no longer crashes
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Deep in the bowels of algsys, function callsolve returns 3 solutions. One of them gets lost on the way back. Maxima 5.47.0 https://maxima.sourceforge.io using Lisp CLISP 2.49+ (2010-07-17) 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) display2d:false$ (%i2) eq1:x^3+x^2-x+%pi-1$ (%i3) ?trace(?callsolve)$ ;; Tracing function CALLSOLVE. (%i4) algsys([eq1],[x]); 1. Trace:...
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Another related bug. algsys only finds two solutions of the cubic x^3+x^2-x+%pi-1. Solve returns three, as expected. This is now bug [#4252] Maxima 5.47.0 https://maxima.sourceforge.io using Lisp CLISP 2.49+ (2010-07-17) 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) display2d:false; (%o1) false (%i2) eq1:x^3+x^2-x+%pi-1$ (%i3) algsys([eq1],[x]); (%o3) [[x = -((2^(2/3)*(3^(9/2)*sqrt(27*%pi^2-32*%pi)+729*%pi-432)^(1/3)...
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algsys only returns 2 (of 3) solutions of a cubic
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Another related bug. algsys only finds two solutions of the cubic x^3+x^2-x+%pi-1. Solve returns three, as expected. Maxima 5.47.0 https://maxima.sourceforge.io using Lisp CLISP 2.49+ (2010-07-17) 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) display2d:false; (%o1) false (%i2) eq1:x^3+x^2-x+%pi-1$ (%i3) algsys([eq1],[x]); (%o3) [[x = -((2^(2/3)*(3^(9/2)*sqrt(27*%pi^2-32*%pi)+729*%pi-432)^(1/3)...
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Another related bug. algsys only finds two solutions of the cubic x^3+x^2-x+%pi-1. Solve returns three. Maxima 5.47.0 https://maxima.sourceforge.io using Lisp CLISP 2.49+ (2010-07-17) 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) display2d:false; (%o1) false (%i2) eq1:x^3+x^2-x+%pi-1$ (%i3) algsys([eq1],[x]); (%o3) [[x = -((2^(2/3)*(3^(9/2)*sqrt(27*%pi^2-32*%pi)+729*%pi-432)^(1/3)...
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I have had a quick look at this. The problem is in the back-substitution phase of algsys - probably while checking that potential solutions satisfy the equations. We can eliminate y to obtain the cubic equation x^3+x^2-x+%pi-1 (%i1) display2d:false$ (%i2) eq1:x = 1-%pi*y$ (%i3) eq2:1 = (x+1)^2*y$ (%i4) solve(eq1,y); (%o4) [y = -((x-1)/%pi)] (%i5) eq2,%; (%o5) 1 = -(((x-1)*(x+1)^2)/%pi) (%i6) %pi*%; (%o6) %pi = -((x-1)*(x+1)^2) (%i7) expand(lhs(%)-rhs(%)); (%o7) x^3+x^2-x+%pi-1 A trace on ?algsys...
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solve can't solve polynomial system of 4 eqs
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Unsure which lisp is giving this error. The code in question is around line 663 of https://sourceforge.net/p/maxima/code/ci/master/tree/share/contrib/diffequations/odelin.lisp (defun hypergeo21-xi-denom-filter (n) (declare (ignore n)) 0) (defun hypergeo21-xi-degree-bound (q v x) (declare (ignore q v x)) 1)
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Last post moved to new bug [#4242 ] as it is not related.
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STYLE-WARNING in share/contrib/diffequations/odelin.lisp
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STYLE-WARNING in share/contrib/diffequations/odelin.lisp
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missing sign functions
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zeroequiv(jacobi_dn(x,1/2),x) crashes with stack overflow
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bessel_simplify error
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Fixed with commit [1d63a5]
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[bugs:#4184] function f is local in ode_check_tidy and bessel_simplify
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contrib_ode testsuite issue addressed in commit [80b8f1]
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{bugs:#4186] Adjust assumption for Kamke 2.405 due to changes elsewhere
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