# All Questions

51 views

### Solving differential equation (Analytical or Numerical)

I want to solve the following differential equation for $0 < x < 1$ ...
58 views

### NDSolve Problems with Cardiovascular Modeling [duplicate]

I am trying to use 27 simultaneous differential equations to model the cardiovascular system. I have the following code, however, the output isn't giving interpolating functions, but rather another ...
36 views

### SetDirectory[NotebookDirectory[]] in one notebook causes Directory[] to change in a different notebook

This is causing me lots of problems. I found that issuing SetDirectory[NotebookDirectory[]]; in notebook A.nb causes subsequent ...
62 views

### Why are these methods giving me different results? (Trying to test SplineFit)

I am creating a polymer(where each monomer is of equal length) using this method: ...
119 views

### Evaluate a expression split in a list

I have a list with this format {integer, sign, integer, sign, integer}, sign being one of these: Plus, Subtract, Times, Divide. For example, let's say: ...
100 views

### Why is Thread[{ a, b }] the same as Transpose[{ a, b }]?

I understand the idea of both Thread and Transpose, but do not understand whatever nuance it is that makes Thread[{ a, b }] == Transpose[{ a, b }] Where ...
300 views

### AJAX-style HTTP calls triggered by a variable change

I'm trying to create a dynamic InputField that would autocomplete the address as I type it into the field, by calling Google Maps' GeoCoding API on every change of ...
46 views

### Stopping sliders in Manipulate going to dynamic unfeasible regions

I am trying to use Manipulate to create a function which allows a user to play with a probability density. The following generates a static density over the range 2000 - 4000, then allows the user to ...
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36 views

### Expression evaluation [closed]

I have got the following solution to an equation: ...
80 views

### Solve an eigensystem faster and eliminate Root[…] from the solution

I have a symbolic, 2-parameter, 8x8 matrix to solve, but Mathematica takes something like 20 minutes to solve it and returns a very large output containing expressions of the form ...
56 views

### ListLogLinearPlot with customize Mesh mix up the markers in multiple curve

I have to plot several curves in logarithmic scale. I used ListLogLinearPlot and customized the Mesh option. Then the markers mixed up. ...
67 views

### Memory usage optimization for a large Association/SparseArray

Reformulating my question in simpler terms. Take two lists list1 = RandomInteger[{1, 100000000}, 25000000]; list2 = RandomReal[{1, 10}, 25000000]; Make an ...
15 views

### How to plot y=y[x] from f[x_,y_]=f0 [duplicate]

Given a two-variable function f[x_,y_]:=(*complicated stuff in terms of x and y *) what I want is to do is Plot ...
39 views

### How to simplify and evaluate Integral with lots of DiracDelta dists

I have a question about an Integrals which I can do by hand but I want to implement this Integral in Mathematica. Actually it is the definition of a 2 Particle Phase Space. The Expression is the ...
128 views
+50

### Confirming conservation laws for complex valued functions

Consider the nonlinear Schrödinger equation (I would like to do this for a more complicated set of equations, but to gain understanding I'll consider this simplified case) $$A_t+iA_{xx}+i|A|^2A =0,$$ ...
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### MeshFunction at azimuthal angles for RegionPlot3D

Edit: I said "polar angle"... It should be "Azimuthal angle". Sorry. I want to plot a Mesh line at a certain azimuthal angle in RegionPlot3D. My goal is to ...
42 views

### Integrate and NIntegrate combined, giving MaxPrecision error

I am trying to integrate the following : ...
63 views

### Can I Adjust Thickness of Spheres and Cylinders to Make Objects Printable in 3D?

I have a design of a crystal structure using Sphere and Cylinder in Mathematica. I then exported the result as an STL file and tried to print it. I was told that the objects were "too thin," that ...
33 views

### Why is there a different eigenvector for the same matrix? [duplicate]

I have a matrix that depends on two variables x and y. Matrix[x,y] When I make x=-.25*(1 - 1/3) + .25*(1/3) + .25 y=0 I ...
25 views

### Extracting coefficients of very large polynomials (perhaps by improving Expand or ExpandAll)

Is there a way to improve or bypass Expand (or ExpandAll) for extremely large polynomials? I have a polynomial system of the form $$0 = \sum_n a_n d_{i_1,i_2} \cdots d_{i_{p-1},i_p},$$ in which ...
225 views

### How to iterate over the columns of a Dataset?

I have a Dataset with a simple structure, like this: ...
79 views

### What do RecursionLimit and IterationLimit actually set?

The following recursive functions respectively calculate the length of a Short-cut Collatz Conjecture series and perform a pointless demonstration recursion: ...
210 views

### How do I create a triangulated surface from points?

I have a set of points in a nx3 matrix and I would like to convert them into a surface, so that I may calculate its surface area. The function ListSurfacePlot3D creates the surface how I want it. ...
31 views

### How can one make NDSolve spend less time at irrelevant transient oscillation?

In the solution there is a transient oscillation that is irrelevant. NDSolve spends a lot of time there. Is there a way to optimize it?
78 views

### Better to use loop or function when populated list?

In the past I have pretty much stuck to expression building when using Mathematica, but recently I have been writing a procedure to populate an array, which I guess are called "lists" in Mathematica. ...
67 views

### Problems with finding the real solutions of equation

I am trying to find real solutions of equation using Mathematica 8.0 but there is some problem I don't know how to explain. For example, for the input ...
1k views

### Why do Mathematica list indices start at 1? [closed]

In most programming languages, container indices start at 0. This is not random or hardware-related; for example Dijkstra's article explains why zero-based indices make sense. What are the reasons ...
35 views

### Unexpected ReplaceAll behavior with NSolve

I ran into some unexpected behavior using ReplaceAll with an equation of motion using NSolve (or Solve, also). First solving for the initial velocity v0: ...
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### Concatenated rule applications (applying rules to rules correctly)

I am trying to apply a series of individual rules onto an expression sequentially, but also not have to write out the repeated ReplaceAll functions each time I want ...
104 views

### Matrix Plot: How to Apply color function to only a region of the plot

I want to make a matrix plot where a color function is applied to a region of a matrix. Those matrix elements which were not in the region specified should not have any color associated with them, and ...