If you have special‐purpose programs written in C or Fortran, you may want to take formulas you have generated in the Wolfram Language and insert them into the source code of your programs. The Wolfram Language allows you to convert mathematical expressions into C and Fortran expressions.
|CForm[expr]||write out expr so it can be used in a C program|
|FortranForm[expr]||write out expr for Fortran|
|Export[file,expr,"C"]||write out a C function that computes expr|
One of the common motivations for converting Wolfram Language expressions into C or Fortran is to try to make them faster to evaluate numerically. But the single most important reason that C and Fortran can potentially be more efficient than the Wolfram Language is that in these languages the user always specifies up front what type each variable will be—integer, real number, array, and so on.
The Wolfram Language function Compile makes such assumptions within the Wolfram Language, and generates highly efficient internal code. This can be made to run even faster by setting the CompilationTarget to "C".
|Compile[x,expr]||compile an expression into efficient internal code|
|Compile[x,expr,CompilationTarget->"C"]||compile into C code and link back into the Wolfram Language|