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May
16
awarded  Nice Answer
May
16
awarded  Nice Answer
May
16
awarded  Nice Answer
May
14
answered Problem with Erf near Infinity in NSolve
May
14
comment Problem with Erf near Infinity in NSolve
Try cc[x_] := -Erfc[x] instead.
May
13
comment How to NIntegrate a function that is the result of another NIntegration
Why not just NIntegrate[y f[x] Exp[I k y Sin[x]] Conjugate[f[z]] Exp[-I k y Sin[z]], {x, a, b}, {z, a, b}, {y, c, d}]?
May
13
comment How to solve numerically an equation which contains numerical intergration?
For one thing, DSolve is for solving differential equations. For another, an equation with a non-analytical integral is probably too hard for Solve and NSolve. Try FindRoot[..., {x, 1}].
May
11
comment Contour plotting temperature data on a hemisphere or circle
Related: Density plot on the surface of sphere
May
11
comment Computing symbolic surface normal of a surface point on a semialgebraic set
If $(x,y,z)$ is a point on the surface $f(x,y,z)=0$, then the surface normal at $(x,y,z)$ is $\nabla f(x,y,z)/\|\nabla f(x,y,z)\|$. So you just have to decide which of your three conditions is active at $(x,y,z)$ and use its normalized gradient.
May
7
comment How to stop optimization (e.g. NMinimize) after reaching target value
FindInstance[f[x, y] <= -5, {x, y}]?
May
6
comment Build an InterpolatingFunction with ElementMeshInterpolation
I guess you could build a list of 2D interpolating functions using ElementMeshInterpolation, and then interpolate between their values in t?
May
5
revised Solving a system of ode and plotting the nullclines
added 107 characters in body
May
5
comment Removing solutions which are particular cases of others
Do you also know for each solution what the free variables (C[1], C[2], etc.) are?
May
1
comment ParametricPlot3D of Boy's surface
You could also add the option RegionFunction -> Function[{x, y, z, u, v}, u^2 + v^2 <= 1] instead of changing the function.
May
1
comment ParametricPlot3D of Boy's surface
Your first problem is that vI is a different variable name; you need v I with a space in between.
Apr
26
comment How do I plot an expression in mathematica?
Plot expects real-valued functions only. What sort of plot do you want to draw for a complex-valued function?
Apr
25
comment Output an Expression in terms of GoldenRatio
I wonder if Simplify's ComplexityFunction option can be useful here?
Apr
25
comment How to fit a surface to 3D data in Mathematica?
Thanks for fixing the error! Sorry my question was unclear. I understand the quadratic transformation of the data, what I want to know is why you are working with only the subset of the data that lies on the convex hull. If I construct mod using data instead of chv it works fine and I get a better estimate of the volume.
Apr
25
comment How to fit a surface to 3D data in Mathematica?
I think you forgot the definition of f. Also, why not apply LinearModelFit directly to the data points rather than to the vertices of the convex hull?
Apr
24
comment How to draw a tropical surface?
This is fun! $(x^2-y^2,y^2-z^2+1,z^2-x^2-1)$: i.stack.imgur.com/MBoL0.png