Re: How to get data from solvin' numerically differential

*To*: mathgroup at smc.vnet.net*Subject*: [mg104146] Re: How to get data from solvin' numerically differential*From*: Leonid Shifrin <lshifr at gmail.com>*Date*: Wed, 21 Oct 2009 06:28:58 -0400 (EDT)*References*: <200910200852.EAA06203@smc.vnet.net>

Hi Mikhail, The easiest probably is to use Put to store the definition (InterpolatingFunction object), and later Get to load it into another Mathematica session. I use it all the time and it works really well for me. Here is a working example which will likely work on your machine without any modification (provided that you have the administrator rights - you may want to alter the base directory through the BaseDirectory option, I set it to $UserBaseDirectory by default). The code below makes a few utility functions to conveniently work with temporary (test) directories Unprotect[BaseDirectory]; ClearAll[dirExistsQ, createTestDir, removeTestDir, getBaseDir, BaseDirectory]; Protect[BaseDirectory]; Options[dirExistsQ] = Options[createTestDir] = Options[removeTestDir] = Options[getBaseDir] = {BaseDirectory -> $UserBaseDirectory}; getBaseDir[OptionsPattern[]] := If[# === $UserBaseDirectory, ToFileName[{#, "Applications"}], #] &[OptionValue[BaseDirectory]]; dirExistsQ[dirName_String, opts : OptionsPattern[]] := Select[FileNames["*", {getBaseDir[opts]}], FileType[#] === Directory && Last[FileNameSplit[#]] === dirName &] =!= {}; createTestDir::exists = "The directory `1` already exists"; createTestDir[dirName_String, opts : OptionsPattern[]] /; ! dirExistsQ[dirName, opts] := CreateDirectory[ToFileName[{getBaseDir[opts], dirName}]]; createTestDir[dirName_String, opts : OptionsPattern[]] := (Message[createTestDir::exists, dirName]; ToFileName[{getBaseDir[opts], dirName}]) removeTestDir::nodir = "No directory was found with the name `1`"; removeTestDir[dirName_String, opts : OptionsPattern[]] /; dirExistsQ[dirName, opts] := DeleteDirectory[ToFileName[getBaseDir[opts], dirName], DeleteContents -> True]; removeTestDir[dirName_String, OptionsPattern[]] := "never happens" /; Message[removeTestDir::nodir, dirName]; The example proper: In[1]:= f=Interpolation[{#,Sin[#]}&/@N[Range[0,2*Pi,2*Pi/100]]] Out[1]= InterpolatingFunction[{{0.,6.28319}},<>] In[2]:= Plot[f[x],{x,0,2Pi}] Output suppressed In[3] = (* Create a test directory if it does not exist, and choose a test file name *) testdir = createTestDir["Test"]; testfile = "testFile.dat"; testfileName = ToFileName[testdir, testfile]; (* Save your definition *) Put[f, testfileName]; Clear[f]; The following code models another Mathematica session (you may indeed restart Mathematica but then you will have to re-run the In[3] code to define testfileName, or indicate it by hand ) In[4] := ClearAll[g]; g = Get[testfileName] Out[4] = InterpolatingFunction[{{0.,6.28319}},<>] In[5] = Plot[g[x], {x, 0, 2 Pi}] Output suppressed Remove the test directory if it is no longer needed In[6] = removeTestDir["Test"] Of course, normally you know the directory where you want to store your files, so you just use Put and Get. I posted the above code just to provide a self-contained working example independent of a particular machine or directory structure. In some cases (but probably not in this one), particularly when you want to save the definitions of a DownValues or SubValues-based functions (or generally, some global definitions), using Save instead of Put may be more appropriate. Hope this helps. Regards, Leonid 2009/10/20 =D0=9C=D0=B8=D1=85=D0=B0=D0=B8=D0=BB =D0=A8=D0=B0=D0=BB=D0=B0=D0= =B3=D0=B8=D0=BD=D0=BE=D0=B2 <shalm89 at gmail.com> > Hi, > Mathematica solves numerically differential equation and makes > interpolation. I can plot this interpolating function. Can I save all > the points in a file or somehow get this data? > Best regards, Mikhail Shalaginov. > >

**References**:**How to get data from solvin' numerically differential equation?***From:*ÐÐÑÐÐÐ ÐÐÐÐÐÐÐÐÐ <shalm89@gmail.com>