CHEBINT: a MATLAB/Octave toolbox for fast multivariate Chebyshev approximation CHEBINT is a MATLAB/Octave toolbox that provides a user-friendly interface to multivariate Chebyshev approximations. It features highly efficient, fast FFT-based, algorithms to determine the approximation (see [2]) that are based on the theory of Chebyshev lattices as introduced in [1]. The approximations itself can then be manipulated, somehow similarly to symbolic equations: the toolbox provides definite/indefinite integration and differentiation, and basic operators like addition, subtraction, multiplication and division (as described in [3]).