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POhow to avoid static member function when using gsl with c++
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copied!<p>I would like to use GSL within a c++ class without declaring member functions as <code>static</code>. The reason for this is because I don't know them too well and I'm not sure about thread safety. From what I read, <code>std::function</code> might be a solution but I'm not sure how to use it.</p> <p>My question comes down to how can I remove <code>static</code> in declaration of <code>g</code>?</p> <pre><code>#include<iostream> #include <functional> #include <stdlib.h> #include <gsl/gsl_math.h> #include <gsl/gsl_monte.h> #include <gsl/gsl_monte_plain.h> #include <gsl/gsl_monte_miser.h> #include <gsl/gsl_monte_vegas.h> using namespace std; class A { public: static double g (double *k, size_t dim, void *params) { double A = 1.0 / (M_PI * M_PI * M_PI); return A / (1.0 - cos (k[0]) * cos (k[1]) * cos (k[2])); } double result() { double res, err; double xl[3] = { 0, 0, 0 }; double xu[3] = { M_PI, M_PI, M_PI }; const gsl_rng_type *T; gsl_rng *r; ////// the following 3 lines didn't work /////// //function<double(A,double*, size_t, void*)> fg; //fg = &A::g; //gsl_monte_function G = { &fg, 3, 0 }; gsl_monte_function G = { &g, 3, 0 }; size_t calls = 500000; gsl_rng_env_setup (); T = gsl_rng_default; r = gsl_rng_alloc (T); { gsl_monte_plain_state *s = gsl_monte_plain_alloc (3); gsl_monte_plain_integrate (&G, xl, xu, 3, calls, r, s, &res, &err); gsl_monte_plain_free (s); } gsl_rng_free (r); return res; } }; main() { A a; cout <<"gsl mc result is " << a.result() <<"\n"; } </code></pre> <p><strong>Update (1)</strong>:</p> <p>I tried changing <code>gsl_monte_function G = { &g, 3, 0 };</code> to <code>gsl_monte_function G = { bind(&A::g, this,_1,_2,_3), 3, 0 };</code> but it didn't work</p> <p><strong>Update (2)</strong>: I tried using <a href="https://stackoverflow.com/questions/12833707/assigning-stdfunction-to-a-member-function">assigning std::function to a member function</a> but it didn't work either.</p> <p><strong>Update (3)</strong> in the end I wrote a non-member function:</p> <pre><code>double gmf (double *k, size_t dim, void *params) { auto *mf = static_cast<A*>(params); return abs(mf->g(k,dim,params)); //return 1.0; }; </code></pre> <p>It worked but it's a messy solution because I needed to write a helper function. With lambdas,function and bind, there should be a way to have everything logical within the class.</p>

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