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Results tagged with Search options user 57

Questions on the numerical functions of Mathematica, implementing numerical methods and numerical computing with Mathematica.

3
votes
In addition to bill's version, which is probably what I'd do as well, another reasonable possibility would be: Table[ NSolve[-y*16 x^3 - y^2*25 x^2 + 5 == 0, x], {y, {0.1, 0.2, 0.3, 0.4, 0.5, 0 …
answered May 25 '13 by Sjoerd C. de Vries
4
votes
With the current setup you get three different answers: testTable // Union (* ==> {0.001242846719, 0.001242850670, 0.001242854621} *) The problem is that you haven't sufficiently increased the pre …
answered May 21 '12 by Sjoerd C. de Vries
3
votes
If the function is not to wild Interpolation could be of use: t = Table[{x, f[2, x]}, {x, 0, 4, 1/10000.}]; it = Interpolation[t] Large values of second derivatives are probably caused by discontin …
answered Nov 18 '12 by Sjoerd C. de Vries
4
votes
If you use inexact constant in your equation it helps if you increase their accuracy as well. You can do that easily using the backtick notation: z[x_, y_] := Exp[Sin[60.0`200*x]] + Sin[50.0`200*Exp[ …
answered Jul 1 '12 by Sjoerd C. de Vries
9
votes
Welcome in the amazing world of machine precision arithmetic! If you examine the binary representation of both numbers you see the following: RealDigits[1.2, 2] (* {{1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, …
answered Jul 13 '15 by Sjoerd C. de Vries
7
votes
This looks like a numerical precision issue. Various approaches that precisely address this, all yield the same, correct solution: Scaling of the x values: data = {{0, 20}, {20, 10}, {40, 5}, {60, 2 …
answered Jan 27 '16 by Sjoerd C. de Vries
2
votes
I modified your NDSolve a bit for convenience (NDSolveValue to get rid of the rule, and f instead of f[p] to get a pure function): s2[σ_] := NDSolveValue[{f''[p] - 2 f[p] f'[p] + (1 + d/2) f[p] + ( …
answered Oct 17 '15 by Sjoerd C. de Vries
21
votes
My variant of Szabolcs code. It doesn't need an extra package: sol = First[ NDSolve[eqns, {a, b}, {t, 0, 1000}, Method -> {"EventLocator", "Event" -> Abs[a'[t]] +Abs[b'[t]] < 10^-5, …
answered Jan 22 '12 by Sjoerd C. de Vries
13
votes
You are talking about a list of 3D points and curve fitting. I therefore assume you want a function with a single parameter that describes a curve fitting through your set of points. I don't believe L …
answered Sep 5 '12 by Sjoerd C. de Vries