## [Maxima-bugs] [ maxima-Bugs-3395683 ] as of Maxima-5.21.1, depends() does not allow a similarity t

 [Maxima-bugs] [ maxima-Bugs-3395683 ] as of Maxima-5.21.1, depends() does not allow a similarity t From: SourceForge.net - 2011-08-24 13:54:29 ```Bugs item #3395683, was opened at 2011-08-21 11:29 Message generated for change (Comment added) made by nldias You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&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 - Simplification Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nelson Luís Dias (nldias) Assigned to: Nobody/Anonymous (nobody) Summary: as of Maxima-5.21.1, depends() does not allow a similarity t Initial Comment: Hi: my name is Nelson Dias, and I am an Associate Professor in Environmental Engineering at the Federal University of Paraná, Brazil. Below is a classical problem: it transforms the PDE (dPsi/dy)(d^2Psi/dxdy) - (dPsi/dx)(d^2Psi/dy^2) - nu*(d^3Psi/dy^3) = 0 into the ODE 2f''' + f f'' = 0 through the similarity transform U = U*delta*eta, delta = (nu*x/U)^(1/2), eta = y/delta. This is the classical Blasius solution for a laminar boundary-layer. The code below transforms the PDE into the ODE: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ delta : (nu*x/U)^(1/2)\$ eta : y/delta\$ depends(f,eta)\$ psi : U*delta*f\$ eq : diff(psi,y) * diff(psi,x,1,y,1) - diff(psi,x)*diff(psi,y,2) - nu*diff(psi,y,3)\$ factor(eq); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In Maxima 5.20.1 it gives the right answer: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) batching /home/nldias/software/maxima-5.20.1/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) (%i5) psi : U delta f (%i6) eq : - nu diff(psi, y, 3) - diff(psi, x) diff(psi, y, 2) + diff(psi, y) diff(psi, x, 1, y, 1) (%i7) factor(eq) 3 2 d f d f 2 (2 -------------- + f --------------) U y 3 y 2 d(----------) d(----------) nu x nu x sqrt(----) sqrt(----) U U (%o7) - ---------------------------------------- 2 x ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ but it fails for all the following versions: 5.21.1 5.22.1 5.23.2 5.24.0 5.25.0 giving the following error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) read and interpret file: /home/nldias/software/maxima-5.25.0/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) y depends: argument must be a symbol; found ---------- nu x sqrt(----) U -- an error. To debug this try: debugmode(true); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I don't know if this is a bug, but if it is not I would very much like to know what the alternative is for the code I used until Maxima-5.20.1. Similarity transforms are a big deal to me, and I would like to be able to continue to use this (and other Maxima examples) in my classes. Sincerely Nelson L. Dias ---------------------------------------------------------------------- Comment By: Nelson Luís Dias (nldias) Date: 2011-08-24 11:54 Message: Barton, thanks a lot for the alternative; I was not aware about pdiff. Regards Nelson ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2011-08-24 07:52 Message: Here is a workaround: (%i45) load(pdiff)\$ (%i46) U * (nu*x/U)^(1/2) * F(y/(nu*x/U)^(1/2))\$ (%i47) diff(%,y) * diff(%,x,1,y,1) - diff(%,x)*diff(%,y,2) - nu*diff(%,y,3)\$ (%i48) ratsubst(w,y/sqrt((nu*x)/U),%)\$ (%i49) solve(%,diff(F(w),w,3)); (%o49) [F[(3)](w)=-(F(w)*F[(2)](w))/2] If you have questions about this, send a note to the mailing list. ---------------------------------------------------------------------- Comment By: Dieter Kaiser (crategus) Date: 2011-08-21 20:02 Message: Thank you very much for your bug report. I had a look at the problem. Because of a bug report the routine i-\$dependencies has been reworked in 14.12.2009. At this time a check has been added to allow only dependencies from a symbol and not an expression. This might be too restrictive, but on the other hand, if we allow dependencies on expressions, we get expressions which have a syntax which is wrong for the function diff. The following is generated with Maxima 5.20: (%i1) depends(f, 2*x); (%o1) [f(2*x)] (%i2) diff(f, x); (%o2) 2*'diff(f,2*x,1) (%i3) ev(%), nouns; diff: second argument must be a variable; found 2*x -- an error. To debug this try: debugmode(true); The problem is that the function diff does not allow the differentiation wrt an expression. Perhaps, we can extend the syntax of the function diff to allow the differentiation wrt an expression. I will think again about this problem. Dieter Kaiser ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&group_id=4933 ```

 [Maxima-bugs] [ maxima-Bugs-3395683 ] as of Maxima-5.21.1, depends() does not allow a similarity t From: SourceForge.net - 2011-08-21 13:29:12 ```Bugs item #3395683, was opened at 2011-08-21 11:29 Message generated for change (Tracker Item Submitted) made by nldias You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&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 - Simplification Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nelson Luís Dias (nldias) Assigned to: Nobody/Anonymous (nobody) Summary: as of Maxima-5.21.1, depends() does not allow a similarity t Initial Comment: Hi: my name is Nelson Dias, and I am an Associate Professor in Environmental Engineering at the Federal University of Paraná, Brazil. Below is a classical problem: it transforms the PDE (dPsi/dy)(d^2Psi/dxdy) - (dPsi/dx)(d^2Psi/dy^2) - nu*(d^3Psi/dy^3) = 0 into the ODE 2f''' + f f'' = 0 through the similarity transform U = U*delta*eta, delta = (nu*x/U)^(1/2), eta = y/delta. This is the classical Blasius solution for a laminar boundary-layer. The code below transforms the PDE into the ODE: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ delta : (nu*x/U)^(1/2)\$ eta : y/delta\$ depends(f,eta)\$ psi : U*delta*f\$ eq : diff(psi,y) * diff(psi,x,1,y,1) - diff(psi,x)*diff(psi,y,2) - nu*diff(psi,y,3)\$ factor(eq); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In Maxima 5.20.1 it gives the right answer: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) batching /home/nldias/software/maxima-5.20.1/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) (%i5) psi : U delta f (%i6) eq : - nu diff(psi, y, 3) - diff(psi, x) diff(psi, y, 2) + diff(psi, y) diff(psi, x, 1, y, 1) (%i7) factor(eq) 3 2 d f d f 2 (2 -------------- + f --------------) U y 3 y 2 d(----------) d(----------) nu x nu x sqrt(----) sqrt(----) U U (%o7) - ---------------------------------------- 2 x ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ but it fails for all the following versions: 5.21.1 5.22.1 5.23.2 5.24.0 5.25.0 giving the following error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) read and interpret file: /home/nldias/software/maxima-5.25.0/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) y depends: argument must be a symbol; found ---------- nu x sqrt(----) U -- an error. To debug this try: debugmode(true); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I don't know if this is a bug, but if it is not I would very much like to know what the alternative is for the code I used until Maxima-5.20.1. Similarity transforms are a big deal to me, and I would like to be able to continue to use this (and other Maxima examples) in my classes. Sincerely Nelson L. Dias ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3395683 ] as of Maxima-5.21.1, depends() does not allow a similarity t From: SourceForge.net - 2011-08-21 22:02:34 ```Bugs item #3395683, was opened at 2011-08-21 15:29 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&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 - Simplification Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nelson Luís Dias (nldias) Assigned to: Nobody/Anonymous (nobody) Summary: as of Maxima-5.21.1, depends() does not allow a similarity t Initial Comment: Hi: my name is Nelson Dias, and I am an Associate Professor in Environmental Engineering at the Federal University of Paraná, Brazil. Below is a classical problem: it transforms the PDE (dPsi/dy)(d^2Psi/dxdy) - (dPsi/dx)(d^2Psi/dy^2) - nu*(d^3Psi/dy^3) = 0 into the ODE 2f''' + f f'' = 0 through the similarity transform U = U*delta*eta, delta = (nu*x/U)^(1/2), eta = y/delta. This is the classical Blasius solution for a laminar boundary-layer. The code below transforms the PDE into the ODE: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ delta : (nu*x/U)^(1/2)\$ eta : y/delta\$ depends(f,eta)\$ psi : U*delta*f\$ eq : diff(psi,y) * diff(psi,x,1,y,1) - diff(psi,x)*diff(psi,y,2) - nu*diff(psi,y,3)\$ factor(eq); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In Maxima 5.20.1 it gives the right answer: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) batching /home/nldias/software/maxima-5.20.1/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) (%i5) psi : U delta f (%i6) eq : - nu diff(psi, y, 3) - diff(psi, x) diff(psi, y, 2) + diff(psi, y) diff(psi, x, 1, y, 1) (%i7) factor(eq) 3 2 d f d f 2 (2 -------------- + f --------------) U y 3 y 2 d(----------) d(----------) nu x nu x sqrt(----) sqrt(----) U U (%o7) - ---------------------------------------- 2 x ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ but it fails for all the following versions: 5.21.1 5.22.1 5.23.2 5.24.0 5.25.0 giving the following error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) read and interpret file: /home/nldias/software/maxima-5.25.0/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) y depends: argument must be a symbol; found ---------- nu x sqrt(----) U -- an error. To debug this try: debugmode(true); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I don't know if this is a bug, but if it is not I would very much like to know what the alternative is for the code I used until Maxima-5.20.1. Similarity transforms are a big deal to me, and I would like to be able to continue to use this (and other Maxima examples) in my classes. Sincerely Nelson L. Dias ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2011-08-22 00:02 Message: Thank you very much for your bug report. I had a look at the problem. Because of a bug report the routine i-\$dependencies has been reworked in 14.12.2009. At this time a check has been added to allow only dependencies from a symbol and not an expression. This might be too restrictive, but on the other hand, if we allow dependencies on expressions, we get expressions which have a syntax which is wrong for the function diff. The following is generated with Maxima 5.20: (%i1) depends(f, 2*x); (%o1) [f(2*x)] (%i2) diff(f, x); (%o2) 2*'diff(f,2*x,1) (%i3) ev(%), nouns; diff: second argument must be a variable; found 2*x -- an error. To debug this try: debugmode(true); The problem is that the function diff does not allow the differentiation wrt an expression. Perhaps, we can extend the syntax of the function diff to allow the differentiation wrt an expression. I will think again about this problem. Dieter Kaiser ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3395683 ] as of Maxima-5.21.1, depends() does not allow a similarity t From: SourceForge.net - 2011-08-24 09:52:01 ```Bugs item #3395683, was opened at 2011-08-21 08:29 Message generated for change (Comment added) made by willisbl You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&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 - Simplification Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nelson Luís Dias (nldias) Assigned to: Nobody/Anonymous (nobody) Summary: as of Maxima-5.21.1, depends() does not allow a similarity t Initial Comment: Hi: my name is Nelson Dias, and I am an Associate Professor in Environmental Engineering at the Federal University of Paraná, Brazil. Below is a classical problem: it transforms the PDE (dPsi/dy)(d^2Psi/dxdy) - (dPsi/dx)(d^2Psi/dy^2) - nu*(d^3Psi/dy^3) = 0 into the ODE 2f''' + f f'' = 0 through the similarity transform U = U*delta*eta, delta = (nu*x/U)^(1/2), eta = y/delta. This is the classical Blasius solution for a laminar boundary-layer. The code below transforms the PDE into the ODE: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ delta : (nu*x/U)^(1/2)\$ eta : y/delta\$ depends(f,eta)\$ psi : U*delta*f\$ eq : diff(psi,y) * diff(psi,x,1,y,1) - diff(psi,x)*diff(psi,y,2) - nu*diff(psi,y,3)\$ factor(eq); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In Maxima 5.20.1 it gives the right answer: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) batching /home/nldias/software/maxima-5.20.1/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) (%i5) psi : U delta f (%i6) eq : - nu diff(psi, y, 3) - diff(psi, x) diff(psi, y, 2) + diff(psi, y) diff(psi, x, 1, y, 1) (%i7) factor(eq) 3 2 d f d f 2 (2 -------------- + f --------------) U y 3 y 2 d(----------) d(----------) nu x nu x sqrt(----) sqrt(----) U U (%o7) - ---------------------------------------- 2 x ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ but it fails for all the following versions: 5.21.1 5.22.1 5.23.2 5.24.0 5.25.0 giving the following error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) read and interpret file: /home/nldias/software/maxima-5.25.0/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) y depends: argument must be a symbol; found ---------- nu x sqrt(----) U -- an error. To debug this try: debugmode(true); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I don't know if this is a bug, but if it is not I would very much like to know what the alternative is for the code I used until Maxima-5.20.1. Similarity transforms are a big deal to me, and I would like to be able to continue to use this (and other Maxima examples) in my classes. Sincerely Nelson L. Dias ---------------------------------------------------------------------- >Comment By: Barton Willis (willisbl) Date: 2011-08-24 04:52 Message: Here is a workaround: (%i45) load(pdiff)\$ (%i46) U * (nu*x/U)^(1/2) * F(y/(nu*x/U)^(1/2))\$ (%i47) diff(%,y) * diff(%,x,1,y,1) - diff(%,x)*diff(%,y,2) - nu*diff(%,y,3)\$ (%i48) ratsubst(w,y/sqrt((nu*x)/U),%)\$ (%i49) solve(%,diff(F(w),w,3)); (%o49) [F[(3)](w)=-(F(w)*F[(2)](w))/2] If you have questions about this, send a note to the mailing list. ---------------------------------------------------------------------- Comment By: Dieter Kaiser (crategus) Date: 2011-08-21 17:02 Message: Thank you very much for your bug report. I had a look at the problem. Because of a bug report the routine i-\$dependencies has been reworked in 14.12.2009. At this time a check has been added to allow only dependencies from a symbol and not an expression. This might be too restrictive, but on the other hand, if we allow dependencies on expressions, we get expressions which have a syntax which is wrong for the function diff. The following is generated with Maxima 5.20: (%i1) depends(f, 2*x); (%o1) [f(2*x)] (%i2) diff(f, x); (%o2) 2*'diff(f,2*x,1) (%i3) ev(%), nouns; diff: second argument must be a variable; found 2*x -- an error. To debug this try: debugmode(true); The problem is that the function diff does not allow the differentiation wrt an expression. Perhaps, we can extend the syntax of the function diff to allow the differentiation wrt an expression. I will think again about this problem. Dieter Kaiser ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-3395683 ] as of Maxima-5.21.1, depends() does not allow a similarity t From: SourceForge.net - 2011-08-24 13:54:29 ```Bugs item #3395683, was opened at 2011-08-21 11:29 Message generated for change (Comment added) made by nldias You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&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 - Simplification Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nelson Luís Dias (nldias) Assigned to: Nobody/Anonymous (nobody) Summary: as of Maxima-5.21.1, depends() does not allow a similarity t Initial Comment: Hi: my name is Nelson Dias, and I am an Associate Professor in Environmental Engineering at the Federal University of Paraná, Brazil. Below is a classical problem: it transforms the PDE (dPsi/dy)(d^2Psi/dxdy) - (dPsi/dx)(d^2Psi/dy^2) - nu*(d^3Psi/dy^3) = 0 into the ODE 2f''' + f f'' = 0 through the similarity transform U = U*delta*eta, delta = (nu*x/U)^(1/2), eta = y/delta. This is the classical Blasius solution for a laminar boundary-layer. The code below transforms the PDE into the ODE: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ delta : (nu*x/U)^(1/2)\$ eta : y/delta\$ depends(f,eta)\$ psi : U*delta*f\$ eq : diff(psi,y) * diff(psi,x,1,y,1) - diff(psi,x)*diff(psi,y,2) - nu*diff(psi,y,3)\$ factor(eq); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In Maxima 5.20.1 it gives the right answer: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) batching /home/nldias/software/maxima-5.20.1/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) (%i5) psi : U delta f (%i6) eq : - nu diff(psi, y, 3) - diff(psi, x) diff(psi, y, 2) + diff(psi, y) diff(psi, x, 1, y, 1) (%i7) factor(eq) 3 2 d f d f 2 (2 -------------- + f --------------) U y 3 y 2 d(----------) d(----------) nu x nu x sqrt(----) sqrt(----) U U (%o7) - ---------------------------------------- 2 x ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ but it fails for all the following versions: 5.21.1 5.22.1 5.23.2 5.24.0 5.25.0 giving the following error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (%i1) batch(psi-bla.max) read and interpret file: /home/nldias/software/maxima-5.25.0/psi-bla.max nu x 1/2 (%i2) delta : (----) U y (%i3) eta : ----- delta (%i4) depends(f, eta) y depends: argument must be a symbol; found ---------- nu x sqrt(----) U -- an error. To debug this try: debugmode(true); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I don't know if this is a bug, but if it is not I would very much like to know what the alternative is for the code I used until Maxima-5.20.1. Similarity transforms are a big deal to me, and I would like to be able to continue to use this (and other Maxima examples) in my classes. Sincerely Nelson L. Dias ---------------------------------------------------------------------- Comment By: Nelson Luís Dias (nldias) Date: 2011-08-24 11:54 Message: Barton, thanks a lot for the alternative; I was not aware about pdiff. Regards Nelson ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2011-08-24 07:52 Message: Here is a workaround: (%i45) load(pdiff)\$ (%i46) U * (nu*x/U)^(1/2) * F(y/(nu*x/U)^(1/2))\$ (%i47) diff(%,y) * diff(%,x,1,y,1) - diff(%,x)*diff(%,y,2) - nu*diff(%,y,3)\$ (%i48) ratsubst(w,y/sqrt((nu*x)/U),%)\$ (%i49) solve(%,diff(F(w),w,3)); (%o49) [F[(3)](w)=-(F(w)*F[(2)](w))/2] If you have questions about this, send a note to the mailing list. ---------------------------------------------------------------------- Comment By: Dieter Kaiser (crategus) Date: 2011-08-21 20:02 Message: Thank you very much for your bug report. I had a look at the problem. Because of a bug report the routine i-\$dependencies has been reworked in 14.12.2009. At this time a check has been added to allow only dependencies from a symbol and not an expression. This might be too restrictive, but on the other hand, if we allow dependencies on expressions, we get expressions which have a syntax which is wrong for the function diff. The following is generated with Maxima 5.20: (%i1) depends(f, 2*x); (%o1) [f(2*x)] (%i2) diff(f, x); (%o2) 2*'diff(f,2*x,1) (%i3) ev(%), nouns; diff: second argument must be a variable; found 2*x -- an error. To debug this try: debugmode(true); The problem is that the function diff does not allow the differentiation wrt an expression. Perhaps, we can extend the syntax of the function diff to allow the differentiation wrt an expression. I will think again about this problem. Dieter Kaiser ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3395683&group_id=4933 ```

No, thanks