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11h
comment How to tell NDSolve about known relations of the exact solution
I don't understand how that is useful. When the order of the equation system is reduced to 3, how would I know what the sign of the Sqrt is? It's needed for both y'[t] and x''[t], so only x'[t]and k[t] is available to determine it, which I believe is impossible?!
13h
revised How to tell NDSolve about known relations of the exact solution
edited title
14h
asked How to tell NDSolve about known relations of the exact solution
Aug
9
asked Problem with grid alignment
Aug
1
answered how to extract a matrix and a vector from a vector
Jul
29
revised Need an efficient way to do this list manipulation
added 121 characters in body
Jul
29
revised Need an efficient way to do this list manipulation
added 27 characters in body
Jul
29
revised Need an efficient way to do this list manipulation
added 129 characters in body
Jul
29
answered Need an efficient way to do this list manipulation
Jul
29
answered How do I solve for one variable in terms of other variables in Mathematica?
Jul
28
comment Using select to pick out elements of nested lists in an odd way
This does it: Cases[{{{A, B}, {A, D}}, {{C, D}, {A, A}, {H, A}}, {{A, H}}}, {___, {A, _}, ___, {A, _}, ___}]
Jul
28
accepted Which function definition is used to evaluate an expression that matches the lefthand side of more than one definition?
Jul
27
asked Which function definition is used to evaluate an expression that matches the lefthand side of more than one definition?
Jul
6
comment How to avoid plotting lines not defined in a Which function?
Use option: Exclusions -> None
Jul
2
awarded  Curious
Jun
11
comment Determine Functions Given Data Points
The constant function f[x,y]=0 contains those solution, and is found by mathematica using InterpolatingPolynomial: InterpolatingPolynomial[{{{0, 0.5}, 0}, {{1, 0.5}, 0}, {{0.6, 0.8}, 0}, {{0.4, 0.2}, 0}}, {x, y}]
May
10
accepted Checkbox behaving weird when variables are local
May
10
asked Checkbox behaving weird when variables are local
Apr
27
comment Evaluate differentiation after replacement
With[{y=replacement},D[y,x]]
Apr
16
answered Recover data points from RGBColor of known ColorScheme