This module provides functionality to generate directly compilable code from Sympy expressions. The codegen function is the user interface to the code generation functionality in Sympy. Some details of the implementation is given below for advanced users that may want to use the framework directly.
Note
The codegen callable is not in the sympy namespace automatically, to use it you must first execute
>>> from sympy.utilities.codegen import codegen
Write source code for the given expressions in the given language.
Mandatory Arguments: | |
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Optional Arguments: | |
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sequence of arguments for the routine in a preferred order. A CodeGenError is raised if required arguments are missing. Redundant arguments are used without warning.
If omitted, arguments will be ordered alphabetically, but with all input aguments first, and then output or in-out arguments.
>>> from sympy import symbols
>>> from sympy.utilities.codegen import codegen
>>> from sympy.abc import x, y, z
>>> [(c_name, c_code), (h_name, c_header)] = \
... codegen(("f", x+y*z), "C", "test", header=False, empty=False)
>>> print c_name
test.c
>>> print c_code,
#include "test.h"
#include <math.h>
double f(double x, double y, double z) {
return x + y*z;
}
>>> print h_name
test.h
>>> print c_header,
#ifndef PROJECT__TEST__H
#define PROJECT__TEST__H
double f(double x, double y, double z);
#endif
Here we present the most important pieces of the internal structure, as advanced users may want to use it directly, for instance by subclassing a code generator for a specialized application. It is very likely that you would prefer to use the codegen() function documented above.
Basic assumptions:
The Routine class is a very important piece of the codegen module. Viewing the codegen utility as a translator of mathematical expressions into a set of statements in a programming language, the Routine instances are responsible for extracting and storing information about how the math can be encapsulated in a function call. Thus, it is the Routine constructor that decides what arguments the routine will need and if there should be a return value.
Generic description of an evaluation routine for a set of sympy expressions.
A CodeGen class can translate instances of this class into C/Fortran/... code. The routine specification covers all the features present in these languages. The CodeGen part must raise an exception when certain features are not present in the target language. For example, multiple return values are possible in Python, but not in C or Fortran. Another example: Fortran and Python support complex numbers, while C does not.
Initialize a Routine instance.
A decision about whether to use output arguments or return values, is made depending on the mathematical expressions. For an expression of type Equality, the left hand side is made into an OutputArgument (or an InOutArgument if appropriate). Else, the calculated expression is the return values of the routine.
A tuple of exressions can be used to create a routine with both return value(s) and output argument(s).
The method that activates the code generation is Codegen.write()
Writes all the source code files for the given routines.
The generate source is returned as a list of (filename, contents) tuples, or is written to files (see options). Each filename consists of the given prefix, appended with an appropriate extension.
Each programming language is generated by subclasses of CodeGen.