# How can I find the coefficients which minimize my non elementary integral?

I have the integral which I express in Mathematica code as:

Integrate[
(-((x^2 (c + x^2 (b + a x^2)))/(m + x^2 (v + d x^2))) + Abs[x])^2,
{x, -1, 1}]


I am looking to find the coefficients/constants c, b, a, d, m, and v which minimize this nonelementary integral.

I was thinking I might find a series approximation of the integral, then minimize that, but I'm not sure how to do so using Mathematica.

• as it should be the same as minimizing the norm of $Abs [x]$ and $(x^2 (c + x^2 (b + a x^2)))/(m + x^2 (v + d x^2))$,how about using of NonlinearModelFit? expr = (x^2 (c + x^2 (b + a x^2)))/(m + x^2 (v + d x^2)); input = x; cofs = {a, b, c, d, m, v}; NonlinearModelFit[ {#, Abs[#]} & /@ Range[-1, 1, .01], expr, cofs, input] – Xminer Dec 20 '19 at 1:45

In order to be more specific refering to the answer of @Yusuf, try:

func[x_, a_, b_, c_, d_, m_, v_] =
(-((x^2 (c + x^2 (b + a x^2)))/(m + x^2 (v + d x^2))) +
Abs[x])^2;

nint[a_?NumericQ, b_?NumericQ, c_?NumericQ, d_?NumericQ, m_?NumericQ, v_?NumericQ] :=
NIntegrate[func[x, a, b, c, d, m, v], {x, -1, 1}]

NMinimize[nint[a, b, c, d, m, v],
{{a, 0, 1}, {b, 0, 1}, {c, 0, 1}, {d, 0, 1}, {m, 0, 1}, {v, 0, 1}}]

(*   {0.0000131187, {a -> 1.25015, b -> 2.12136, c -> 0.0859803, d -> 2.75847,
m -> 0.00319823, v -> 0.680549}}   *)


But you have no warranty, that this is a global minimum. Use starting values for the parameters, that make sense according to your problem.

NMinimize[NIntegrate[f[x, a, b, c(*extend to however many coefficients/constants are in your function*)], {x, -1, 1}], {a, b, c(*extend to however many coefficients/constants are in your function here as well*)}]