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Getting Started

Install tax, build the tests, and write your first Taylor expansion.

Requirements

Tool Minimum version
C++ compiler GCC 13, Clang 17, Apple Clang 16 (C++23 with concepts)
CMake 3.28
Eigen 3.4
GoogleTest fetched automatically by CMake if missing

Build & test from source

git clone https://github.com/andreapasquale94/tax.git
cd tax
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j
ctest --test-dir build --output-on-failure

CMake options

Option Default Description
TAX_BUILD_UNITTESTS ON Build the GoogleTest unit-test suite
TAX_BUILD_REGRESSIONS OFF Build the DACE-based regression tests

The fast Cauchy kernel paths (TAX_USE_UNROLL for \(M=1\), TAX_USE_STENCIL for \(M \ge 2\)) default to on in <tax/kernels/cauchy.hpp>; pre-define the macro to 0 (identically in every translation unit) to fall back to the loop kernel.

Install and consume from another CMake project

cmake --install build --prefix /your/install/prefix

find_package(tax CONFIG REQUIRED)
target_link_libraries(your_target PRIVATE tax::tax)

If installed to a non-standard prefix:

cmake -S . -B build -DCMAKE_PREFIX_PATH=/your/install/prefix

Your first expansion

Everything is reachable through a single umbrella header:

#include <tax/tax.hpp>          // core type + named expansions + Eigen integration
#include <iostream>

int main() {
    auto x = tax::TE<5>::variable(0.0);   // 5th-order variable at x₀ = 0
    tax::TE<5> f = sin(x);                // propagate the whole Taylor series

    std::cout << f.value()         << '\n';   // sin(0)  = 0
    std::cout << f.derivative<1>() << '\n';   // cos(0)  = 1
    std::cout << f.derivative<3>() << '\n';   // −cos(0) = −1
    std::cout << f.eval(0.3)       << '\n';   // ≈ sin(0.3)
}

One evaluation pass yields the value and every derivative up to order 5.

Next steps