tomsolver

中文 English

Simplest, Well-tested, Non-linear equations solver library by C++14.

origin: https://github.com/tomwillow/tomsolver

Make C++ solve nonlinear equations as easy as Matlab fsolve

Contributors:

Tom Willow (https://github.com/tomwillow)
lizho (https://github.com/lizho)

Features

Simple! Simple! If you know how to use fsolve, you will use this!
Single header file, just include it!

Functions

Solving nonlinear equations (Newton-Raphson method, LM method)
Solving linear equations (Gaussian-column pivot iteration method, inverse matrix)
Matrix and vector operations (matrix inversion, vector cross multiplication, etc.)
"Pseudo" symbolic operations (derivatives of expressions, Jacobian matrices of symbolic matrices)

Supported Platforms

Tested at:

Linux: ubuntu 22.04 x86_64 gcc 11.3.0
Windows: windows10 x64 Visual Studio 2019

Tested at Github Actions:

Linux-latest gcc Debug&Release
Linux-latest clang Debug&Release
Windows-latest msvc Debug&Release

Example

#include <tomsolver/tomsolver.h>

using namespace tomsolver;

int main() {
    /*
    Translate from Matlab code:

    root2d.m:
        function F = root2d(x)
            F(1) = exp(-exp(-(x(1)+x(2)))) - x(2)*(1+x(1)^2);
            F(2) = x(1)*cos(x(2)) + x(2)*sin(x(1)) - 0.5;
        end

    root2d_solve.m:
        format long
        fun = @root2d;
        x0 = [0,0];
        x = fsolve(fun,x0)

    result:
        x =

            0.353246561920553   0.606082026502285
     */
    try {
        // create equations from string
        SymVec f = {
            "exp(-exp(-(x1 + x2))) - x2 * (1 + x1 ^ 2)"_f,
            "x1 * cos(x2) + x2 * sin(x1) - 0.5"_f,
        };

        // solve it!
        VarsTable ans = Solve(f);

        // print the solution
        std::cout << ans << std::endl;

        // get the values of solution
        std::cout << "x1 = " << ans["x1"] << std::endl;
        std::cout << "x2 = " << ans["x2"] << std::endl;
    } catch (const std::runtime_error &err) {
        // if any error occurs, exception will be thrown
        std::cerr << err.what() << std::endl;
        return -1;
    }

    return 0;
}

Usage

1. Header-Only usage

Just include a single header file: single/include/tomsolver/tomsolver.h

2. VCPKG

You could use vcpkg for unified package usage.

Manifest mode(recommended) Create a vcpkg.json file:
```
{
  "dependencies": [
    "tomsolver"
  ]
}
```
Then run the following command in the same directory: $ vcpkg install Tutorial: https://learn.microsoft.com/en-us/vcpkg/get_started/get-started?pivots=shell-bash
Classic mode $ vcpkg install tomsolver

2. Binary Library + Header Files usage

$ git clone https://github.com/tomwillow/tomsolver
$ mkdir build
$ cd build
$ cmake ../tomsolver
$ cmake --build . --target INSTALL

Then add the include directory and link to the library file.

Directory Structure

src: source files
tests: unit tests
single/include: the folder where the header-only tomsolver.h is located
single/test: All unit tests are integrated into one .cpp file to test whether tomsolver.h is correct.
scripts: used to generate single-file header files and single-file tests under single

examples

examples/solve: Example of solving nonlinear equations, demonstrating basic usage and how to set a unified initial value
examples/set_initial_value: Example of solving nonlinear equations, demostrating how to set every variable's initial value
examples/solve2: Example of solving nonlinear equations, demonstrating how to switch solution methods and replace known quantities in the equation
examples/diff_machine: Derivator, input a line of expression and output the derivation result of this expression

Development Plan

add doxygen comments + tutorial document (CN+EN)
add benchmark tests
add an option to use Eigen library as matrix library
aim at Matlab fsolve, add more solving methods of nonlinear equations
add an optional Config parameter in Solve() function (similar to Matlab fsolve's option)
add support for binary/multivariate functions, such as pow(x, y)
the current Simplify function is still very simple, modify Simplify to be better
add LaTeX format formula output

Thanks

https://github.com/taehwan642

WeChat group

If you have any questions, want to communicate, want to participate in development, or want to contact the authors, you are welcome to add the WeChat tomwillow.

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Tomsolver

Install / Use

README