On 14/08/2020 22:56, Anirban Pal via Boost-users wrote:
Hello,
I'm trying to integrate functions with BOOST quadrature routines. So far they have been extremely impressive accuracy-wise, particularly with multiprecision features.
I wish to integrate a function and pass some arguments to it. These arguments can be scalars, matrices, structs or objects. I was wondering if there is an example that explores this. Would I need to use a boost.function? Or would a function pointer work?
To create a reusable single-valued functor that integrates from [a, x] for fixed a, then I think some nested lambda expressions would work: auto integral = [](double x) { // Integrates from 0 to x: static tanh_sinh<double> integrator; static auto f = [](double x) { return 5 * x + 7; }; return integrator.integrate(f, 0.0, x); }; std::cout << integral(2) << std::endl; std::cout << integral(4.5) << std::endl; I'm not sure what you had in mind with non-scalar arguments, but if you need to evaluate the above at multiple x values [x_1, x_2.... x_n] then conceivably you could integrate from [a, x_0] [x_1, x_2] .... [x_n-1, x_n] and then sum to get the integrals [a, x_0] [a, x_1] .... [a, x_n] Which may or may not be more efficient. HTH, John.
I currently have an implementation using GSL_functions which explicitly allow the function and parameters to be passed as pointers. I am curious if I can do something similar with boost.
Thank you.
-- Anirban Pal
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