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DirectSourceGeneration
Direct source generation is only advised for advanced use cases.For most cases, if you are using Linux, there are utility classes that will automatically perform most steps (seeLibGeneration).
The C source generator aims at producing not only efficient source code but also a source code that leads to faster compilations.This is achieved by reducing the total number of temporary variables, including variable reuse, and having very short variable names.
A generic program used to generate C source code can be written as:
#include<iosfwd>#include<vector>#include<cppad/cg.hpp>usingnamespaceCppAD;usingnamespaceCppAD::cg;intmain() {// use a special object for source code generationtypedef CG<double> CGD;typedef AD<CGD> ADCG;/*************************************************************************** * the model **************************************************************************/// independent variable vector CppAD::vector<ADCG>x(2); x[0] =2.; x[1] =3.;Independent(x);// dependent variable vector CppAD::vector<ADCG>y(1);// the model ADCG a = x[0] /1. + x[1] * x[1]; y[0] = a /2; ADFun<CGD>fun(x, y);// the model tape/*************************************************************************** * Generate the C source code **************************************************************************//** * start the special steps for source code generation for a Jacobian*/ CodeHandler<double> handler; CppAD::vector<CGD>indVars(2); handler.makeVariables(indVars); CppAD::vector<CGD> jac = fun.SparseJacobian(indVars); LanguageC<double>langC("double"); LangCDefaultVariableNameGenerator<double> nameGen; std::ostringstream code; handler.generateCode(code, langC, jac, nameGen); std::cout << code.str();}
The output of this function is:
y[1] = 0.5 * x[1] + 0.5 * x[1]; // dependent variables without operations y[0] = 0.5;Make sure to check out theLinux page which is also applicable to macOS.
CppADCodegen, in addition to the highly optimized C sources, is also capable of generating documentation oriented sources. These include:
- LATEX sources, which can be used to compile PDF files,
- HTML documents with presentation MathML markup and Javascript, and
- Dot-files to generate a graph of operations.
CppADCogden can create an HTML page that allows you to navigate your model.Since models can be extremely large (millions of lines of code), this is best suited for small models.
#include<iosfwd>#include<cppad/cg.hpp>#include<cppad/cg/lang/mathml/mathml.hpp>usingnamespaceCppAD;usingnamespaceCppAD::cg;intmain(void) {// use a special object for source code generationusing CGD = CG<double>;using ADCG = AD<CGD>;// independent variable vector CppAD::vector<ADCG>x(2); x[0] =2.; x[1] =3.;Independent(x);// dependent variable vector CppAD::vector<ADCG>y(8);/*************************************************************************** * the model **************************************************************************/ ADCG a = x[0] /1. + x[1] * x[1]; ADCG b = a /2e-6; y[0] = b +1 / (sign(b)*5 * a); y[1] = x[1]; y[2] =CondExpLt(ADCG(1.0), x[0], x[1], b); y[3] =CondExpLe(x[0],ADCG(2.0), x[1], b); y[4] =CondExpEq(x[0], x[1], x[1], b); ADCG c =CondExpGe(ADCG(3.0), x[0], a, b); y[5] =CondExpGt(ADCG(4.0), x[0],ADCG(5.0), c); y[6] =5 *pow(4, x[0]); y[7] =3; ADFun<CGD>fun(x, y);// the model tape/*************************************************************************** * Generate the HTML/MathML source code **************************************************************************/ CodeHandler<double> handler; CppAD::vector<CGD>indVars(2); handler.makeVariables(indVars); CppAD::vector<CGD> vals = fun.Forward(0, indVars); LanguageMathML<double> langMathML; LangMathMLDefaultVariableNameGenerator<double> nameGen; langMathML.setSaveVariableRelations(true);// add some additional code to select variables langMathML.setStyle(langMathML.getStyle() +"\n.selectedProp{background-color: #ccc;}""\n.faded{\n"" opacity: 0.2;\n"" filter: alpha(opacity=20); /* For IE8 and earlier */\n""}\n""\n.faded2{\n"" opacity: 0.5;\n"" filter: alpha(opacity=50); /* For IE8 and earlier */\n""}");// use block display langMathML.setEquationMarkup("<math display=\"block\" class=\"equation\">","</math>");// use MathJax (and align to the left) langMathML.setHeadExtraMarkup("<script type=\"text/x-mathjax-config\">\n"//"MathJax.Hub.Config({ MMLorHTML: { prefer: { Firefox: \"MML\" } } });\n" // use this to define a prefered browser renderer"MathJax.Hub.Config({\n"" jax: [\"input/TeX\",\"output/HTML-CSS\"],\n"" displayAlign:\"left\"\n""});\n""</script>\n""<script type=\"text/javascript\" src=\"https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML\"></script>"); std::ifstream jsFile; jsFile.open("variableSelection.js"); std::stringstream strStream; strStream << jsFile.rdbuf(); langMathML.setJavascript(strStream.str());// create the HMTL file std::ofstream htmlFile; htmlFile.open("algorithm.html"); handler.setReuseVariableIDs(false); handler.generateCode(htmlFile, langMathML, vals, nameGen); htmlFile.close();}
This program creates anHTML file for the model that can be used to navigate and inspect your model.The javascript filevariableSelection.js is available in the test folder.
Here is a screenshot of the result (the variable x0 was selected):
CppADCodeGen can generate Latex files that can be used to create PDF files.These PDF files are better suited for larger models than MathML.
Here is an example:
#include<iosfwd>#include<cppad/cg.hpp>#include<cppad/cg/lang/latex/latex.hpp>usingnamespaceCppAD;usingnamespaceCppAD::cg;intmain(void) {// use a special object for source code generationusing CGD = CG<double>;using ADCG = AD<CGD>;/*************************************************************************** * the model **************************************************************************/// independent variable vector CppAD::vector<ADCG>x(2); x[0] =2.; x[1] =3.;Independent(x);// dependent variable vector CppAD::vector<ADCG>y(1);// the model ADCG a = x[0] /1. + x[1] * x[1]; y[0] = a /2; ADFun<CGD>fun(x, y);// the model tape/*************************************************************************** * Generate the Latex source code **************************************************************************//** * start the special steps for source code generation*/ CodeHandler<double> handler; CppAD::vector<CGD>xv(x.size()); handler.makeVariables(xv); CppAD::vector<CGD> vals = fun.Forward(0, xv); LanguageLatex<double> langLatex; LangLatexDefaultVariableNameGenerator<double> nameGen; std::ofstream texfile; texfile.open("algorithm.tex"); handler.generateCode(texfile, langLatex, vals, nameGen); texfile.close();/*************************************************************************** * Compile a PDF file **************************************************************************/#ifdef PDFLATEX_COMPILER std::string dir =system::getWorkingDirectory();system::callExecutable(PDFLATEX_COMPILER, {"-halt-on-error","-shell-escape",system::createPath({dir,"resources"},"latex_template.tex")});#endif}
This program expectsPDFLATEX_COMPILER to be set to a Latex compiler (e.g., /usr/bin/pdflatex) and a template file (seelatex_template.tex) to be provided.It then creates aPDF file.