Re: Traditional Ordering of Equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg88818] Re: Traditional Ordering of Equations*From*: Szabolcs Horvát <szhorvat+mathgroup at gmail.com>*Date*: Sat, 17 May 2008 05:31:46 -0400 (EDT)*Organization*: University of Bergen*References*: <g0jk79$ta$1@smc.vnet.net>

Joost Keuskamp wrote: > As a beginner in Mathematica I am using Mathematica 6.0 for integration and simplification of a number of functions which I subsequently use in a Fortran program. Now I have two questions which I cannot find the answer to in the documentation or forums: > > - Is there a way to prevent Mathematica from reordering a function to its standard order upon evaluation? > > - I want to list all resulting functions in one cell, as can be done using the Print and Fortranform commands. I want the list to look like this: > > > FunctionName1 = Function1 > FunctionName2 = Function2 > FunctionName3 = Function3 > etc. > > All these functions were defined earlier in the notebook using the following syntax: > > FunctionName1 = Function1 > > I tried writing a new Mathematica function to do this: > > FortranFormulas[ff_] := This line, > Print[HoldForm[ff] "=" FortranForm[ff]] is equivalent to Print[ HoldForm[ff] * "=" * FortranForm[ff] ]. Multiplication is commutative, so Mathematica will automatically sort the three terms. You probably meant Print[HoldForm[ff], "=", FortranForm[ff]] instead. > FunctionNameList = {NO3inYt, NO3outYt} > Scan[FortranFormulas, FunctionNameList] > > However, this generates an output like: > = Function1inFortranForm Function1 > = Function2inFortranForm Function2 > > The alternative: > FortranFormulas[ff_] := > Print[ff] "=" FortranForm[Release[ff]]] Again, the syntax appears to be incorrect here ... > FunctionNameList = {HoldForm[NO3inYt], HoldForm[NO3outYt]} > Scan[FortranFormulas, FunctionNameList] > > generates an output like: > = FunctionName1 FunctionName1 > = FunctionName2 FunctionName2 > > Both are incorrect and in the wrong order. > > I don't know what to do now and was hoping that anyone had a suggestion.. ..many thanks in advance! > Here's a way to do this: First, let's produce some pretty formulae to experiment with: y = HornerForm[LegendreP[6, x]] z = TrigExpand[Cos[6 x]] The key is to set the attribute HoldAll on the function: ClearAll[fortranFormulas] SetAttributes[fortranFormulas, HoldAll] fortranFormulas[ff_] := Print[HoldForm[ff], " = ", FortranForm[ff]] Now one way to use the function on a list is to wrap all symbols in Hold, as you did: fortranFormulas @@@ {Hold[y], Hold[z]} But it may be more convenient (less typing with long lists) to just use strings: Scan[ToExpression[#, InputForm, fortranFormulas] &, {"y", "z"}]