Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Favorites infavorites:mine
infavorites:1234
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with Search options user 57

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

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 …
modified 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] + ( …
modified Oct 17 '15 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, …
modified Jul 13 '15 by Sjoerd C. de Vries
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 …
modified May 25 '13 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 …
modified Nov 18 '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 …
modified Sep 5 '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[ …
modified Jul 1 '12 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 …
modified May 21 '12 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, …
modified Jan 22 '12 by Sjoerd C. de Vries