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Results for interpolationpointssubdivision
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1 vote
0 answers
61 views

Why does the InterpolationPointsSubdivision method fails to calculate this integral correctly?

", ySpectrum["InterpolationPointsSubdivision",0.2,0.3] gives zero, while ySpectrum["AdaptiveMonteCarlo",0.2,0.3] is non-zero (as it should be, if looking at the initial data). … But how to make "InterpolationPointsSubdivision" work correctly? It does not work properly with non-rectangular regions of integration. …
John Taylor's user avatar
  • 5,963
5 votes

How to solve this integral equation using Mathematica?

1}]; var = Flatten[Table[co[i, j], {j, 0, jm, 1}, {i, 0, 2^j - 1, 1}]]; varM = Join[{co[-1, -1]}, var]; eq[x_] := Sum[NIntegrate[Cot[(x - t)/2]*h[t, i, 2^j], {t, -ac, x, ac}, Method -> {"InterpolationPointsSubdivision … ", Method -> {"PrincipalValue", "SymbolicProcessing" -> 0}}]* co[i, j], {j, 0, jm, 1}, {i, 0, 2^j - 1, 1}] + NIntegrate[Cot[(x - t)/2]*h1[t], {t, -ac, x, ac}, Method -> {"InterpolationPointsSubdivision
Alex Trounev's user avatar
  • 48.8k
4 votes
Accepted

Plot nested integration of an InterpolatingFunction efficiently

= s}}], (* subtract singular part *) {s, -L, x, L}, Method -> {"InterpolationPointsSubdivision", (* divide interval at nodes *) "SymbolicProcessing" -> 0}, PrecisionGoal - … = xp}}], {xp, -L, x, L}, Method -> {"InterpolationPointsSubdivision", "SymbolicProcessing" -> 0}, PrecisionGoal -> 4] + dux*((2*L) Log[(L + x)/(L - x)])/π]]; Single-call timings …
Michael E2's user avatar
  • 245k
3 votes

Integral of a Wavelet function

Verify how many interpolation points are used in the integration interval of interest: Count[Flatten[derPhi["Grid"]], x_ /; 1/4 < x < 1/2] 63 We can then use the "InterpolationPointsSubdivision" … The count above is well within the default setting of "MaxSubregions", so that doesn't need to be adjusted: NIntegrate[derPhi[x], {x, 1/4, 1/2}, Method -> {"InterpolationPointsSubdivision" …
5 votes

NIntegrate failed to converge and why?

You can specify the singularities sometimes with Method -> "InterpolationPointsSubdivision", but it does not work here, maybe because of the complexity of p1. …
Michael E2's user avatar
  • 245k
1 vote

Solving PDE and avoiding singularity

NumericQ, t_ /; t == 0] := (cnt++; NIntegrate[inicos'''[xp]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method -> "PrincipalValue"}, PrecisionGoal … NumericQ, t_ /; t == 0] := (cnt++; NIntegrate[ inicos'''[xp]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method -> "PrincipalValue" …
Alex Trounev's user avatar
  • 48.8k
3 votes
1 answer
342 views

Solving PDE and avoiding singularity

NumericQ, t_ /; t == 0] := (cnt++; NIntegrate[inicos'''[xp]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method -> "PrincipalValue"}, PrecisionGoal … NumericQ] := Function[x, cnt++; NIntegrate[Interpolation[periodize@Transpose@{xv, uppp}, xp, PeriodicInterpolation -> True]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision
user55777's user avatar
  • 643
4 votes
1 answer
457 views

How to speed up the integral in NDSolve?

NumericQ, t_ /; t == 0] := (cnt++; c*NIntegrate[D[ic[xp], {xp, 3}]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method -> {"PrincipalValue", " … NumericQ, t_ /; t == 0] := (cnt2++; c*NIntegrate[D[ic[xp], {xp, 2}]*int[D[ic[xp], xp], x, t]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method …
user55777's user avatar
  • 643
11 votes

Solving partial differential equation involving Hilbert transform

NumericQ, t_ /; t == 0] := (cnt++; NIntegrate[-Cos[xp]/ (x - xp), {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method -> "PrincipalValue"}, PrecisionGoal -> 8 … VectorQ, t_] := Function[x, cnt++; NIntegrate[ Interpolation[periodize@Transpose@{xv, uppp}, xp, PeriodicInterpolation -> True]/ (x - xp), {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision
Alex Trounev's user avatar
  • 48.8k
3 votes
Accepted

Interpolation works slowly

weak singularities, which require dense sampling to get an accurate estimate or require the integration region to be broken up according to the pieces of the piecewise interpolation, which is what the "InterpolationPointsSubdivision … i1 = NIntegrate[ DistrToyInterpolated[thh, Eh], {thh, 0, Pi}, {Eh, 125, 3000}, Method -> {"InterpolationPointsSubdivision", "MaxSubregions" -> 315*3000/5, (* slight overestimate from interpolation …
Michael E2's user avatar
  • 245k
5 votes
Accepted

Can I obtain more precise integration of highly oscillating integral?

The "InterpolationPointsSubdivision" preprocessor of NIntegrate seems like the right move, but it was much faster and with a much better result to do a simple, straightforward implementation of an integration …
Michael E2's user avatar
  • 245k
3 votes
Accepted

Integrating over colors

From here, we can use the sRGB conversion functions from this answer, and then use NIntegrate[] with the setting Method -> "InterpolationPointsSubdivision": (* gamma correction *) sRGBGamma = Function … 12.92 z, z <= 0.0031308}}, 1.055 z^(1/2.4) - 0.055]], Listable]; NIntegrate[Clip[#, {0, 1}]/λ^4, {λ, 385, 700}, Method -> "InterpolationPointsSubdivision
10 votes

Solving an integro-differential equation with Mathematica

NumericQ, t_ /; t == 0] := (cnt++; NIntegrate[ D[0.1*Cos[\[Pi]/L*xp], {xp, 3}]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision", Method … cnt++; NIntegrate[ Interpolation[periodize@Transpose@{xv, uppp}, xp, PeriodicInterpolation -> True]*Cot[\[Pi] (x - xp)/(2*L)], {xp, x - L, x, x + L}, Method -> {"InterpolationPointsSubdivision
Michael E2's user avatar
  • 245k
-1 votes
3 answers
925 views

Problem with NIntegrate over a highly-oscillatory integrand

To do that, I the function Si2[a_, b_] := NIntegrate[Sin[x - y]/(x y), {x, a, b}, {y, x, b}, AccuracyGoal -> 25, PrecisionGoal -> 25, WorkingPrecision -> 40, MaxRecursion -> 1000000, Method -> "InterpolationPointsSubdivision … Note that I use the InterpolationPointsSubdivision method because I saw in various answers that it is a good method to evaluate numerically a highly-oscillatory integrand. …
EZLearner's user avatar
  • 295
1 vote

How to speed up integration of interpolation function?

opts = {{}, Method -> "InterpolationPointsSubdivision", {Method -> {Automatic, "SymbolicProcessing" -> 0}, PrecisionGoal -> 3}}; res = Table[ With[{x = 5, y = 5, o1 = o}, Prepend …
Anton Antonov's user avatar

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