Re: A simple quetion
- To: mathgroup at smc.vnet.net
- Subject: [mg17690] Re: A simple quetion
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Fri, 21 May 1999 23:59:04 -0400
- References: <7i3487$bdr@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Nikos, Your code P[a[x]_ y'[x]_+b[x]_ y[x]_+d[x]_,x_]:= Module[{a1,a2}, a1=If[a[x]==x,p[x]==b[x]/a[x];q[x]==d[x]/a[x],y[x]==-d[x]/b[x]]; a2=y[x]==Exp[- Integrate[p[x],x] [c+Integrate[q[x] Exp[Integrate[p[x],x]],x]]]] Requires, for example, the coefficient of y'[x] to be of the form FullForm[a[x]_] Times[a[x],Blank[]] Also names of blanks must be symbols. The following is less demanding, and works Clear["`*"] P[a_ y_'[x_]+b_ y_ [x_]+d_,x_]:=Module[{a1,a2}, a1=If[a==x,p==b/a;q==d/a,y==-d/b]; a2=y==Exp[-Integrate[p,x] [c+Integrate[q Exp[Integrate[p,x]],x]]]] P[x y'[x]+2 y[x]+x^2,x] y == E^(-(p*x)[c + (E^(p*x)*q)/p]) Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 Nikos Skordelis <ma05451 at socrates.cc.uoi.gr> wrote in message news:7i3487$bdr at smc.vnet.net... > > Why the program does not running? It's a simple program about solving > first linear equations. When i call it back with a specific equation it > doesn't returns the solution. Any suggestions about what my mistake is? > Thanks in advance > Skordelis Nikos email:ma05451 at socrates.cc.uoi.gr > > (*********************************************************************** > > Mathematica-Compatible Notebook > > This notebook can be used on any computer system with Mathematica 3.0, > MathReader 3.0, or any compatible application. The data for the notebook > starts with the line of stars above. > > To get the notebook into a Mathematica-compatible application, do one of > the following: > > * Save the data starting with the line of stars above into a file > with a name ending in .nb, then open the file inside the application; > > * Copy the data starting with the line of stars above to the > clipboard, then use the Paste menu command inside the application. > > Data for notebooks contains only printable 7-bit ASCII and can be > sent directly in email or through ftp in text mode. Newlines can be > CR, LF or CRLF (Unix, Macintosh or MS-DOS style). > > NOTE: If you modify the data for this notebook not in a Mathematica- > compatible application, you must delete the line below containing the > word CacheID, otherwise Mathematica-compatible applications may try to > use invalid cache data. > > For more information on notebooks and Mathematica-compatible > applications, contact Wolfram Research: > web: http://www.wolfram.com > email: info at wolfram.com > phone: +1-217-398-0700 (U.S.) > > Notebook reader applications are available free of charge from > Wolfram Research. > ***********************************************************************) > > (*CacheID: 232*) > > > (*NotebookFileLineBreakTest > NotebookFileLineBreakTest*) > (*NotebookOptionsPosition[ 2577, 82]*) > (*NotebookOutlinePosition[ 3225, 105]*) > (* CellTagsIndexPosition[ 3181, 101]*) > (*WindowFrame->Normal*) > > > > Notebook[{ > Cell[BoxData[ > \(Clear[P]\)], "Input"], > > Cell[BoxData[ > \(P[a[x] _\ \(y'\)[x] _ + b[x] _\ y[x] _ + d[x] _, x_] := > Module[{a1, a2}, > a1 = If[a[x] == x, p[x] == b[x]/a[x]; q[x] == d[x]/a[x], > y[x] == \(-d[x]\)/b[x]]; > a2 = y[x] == > Exp[\(-\(Integrate[p[x], x]\)\ [ > c + Integrate[q[x]\ Exp[Integrate[p[x], x]], x]]\)]]\)], > "Input"], > > Cell[BoxData[""], "Input"], > > Cell[BoxData[""], "Input"], > > Cell[CellGroupData[{ > > Cell[BoxData[ > \(P[x\ \(y'\)[x] - 2\ y[x] + x^2, x]\)], "Input"], > > Cell[BoxData[ > RowBox[{"P", "[", > RowBox[{ > RowBox[{\(x\^2\), "-", \(2\ y[x]\), "+", > RowBox[{"x", " ", > RowBox[{ > SuperscriptBox["y", "\[Prime]", > MultilineFunction->None], "[", "x", "]"}]}]}], ",", "x"}], > "]"}]], "Output"] > }, Open ]] > }, > FrontEndVersion->"Microsoft Windows 3.0", > ScreenRectangle->{{0, 640}, {0, 424}}, > WindowSize->{480, 300}, > WindowMargins->{{0, Automatic}, {Automatic, 5}} > ] > > > (*********************************************************************** > Cached data follows. If you edit this Notebook file directly, not using > Mathematica, you must remove the line containing CacheID at the top of > the file. The cache data will then be recreated when you save this file > from within Mathematica. > ***********************************************************************) > > (*CellTagsOutline > CellTagsIndex->{} > *) > > (*CellTagsIndex > CellTagsIndex->{} > *) > > (*NotebookFileOutline > Notebook[{ > Cell[1709, 49, 41, 1, 30, "Input"], > Cell[1753, 52, 358, 8, 110, "Input"], > Cell[2114, 62, 26, 0, 30, "Input"], > Cell[2143, 64, 26, 0, 30, "Input"], > > Cell[CellGroupData[{ > Cell[2194, 68, 67, 1, 30, "Input"], > Cell[2264, 71, 297, 8, 29, "Output"] > }, Open ]] > } > ] > *) > > > > > (*********************************************************************** > End of Mathematica Notebook file. > ***********************************************************************)