14
votes
5answers
695 views

Using ReadList and Skip to read a file with periodic alternation of useful and useless data

I am trying a read a file that's arranged such that there's alternating set of rows containing data that I don't need and data that I need. So for my case the first n lines in the files are useless to ...
6
votes
2answers
2k views

Calculating a minimum bounding box for a set of 3-space coordinates / spheres

I have a set of 3-space coordinates for the atoms of a molecule (I could also transform them into spheres with radii corresponding to the atoms they represent). I would like to place this molecule ...
1
vote
1answer
118 views

Draw only the top of the boundary of a function in Plot3d

So currently I have via combining 3 Plot3D's in a show. My question is how can I make it so that the ONLY portion of that border highlighted green, is the "curving portion" in the xy plane, rather ...
1
vote
1answer
2k views

Importing a matrix from a text file

I have a $4 \times N$ matrix in a .txt file of the form: -17.071 137.567 16.554 0.65 -16.873 136.138 16.934 0.7 -15.397 135.738 16.894 0.7 -14.7 135.982 15.9 0.6 ...
1
vote
2answers
2k views

Finding a best fit curve and plotting it [closed]

I have a list as shown below: m01 = {{250, 0.083121}, {200, 0.0888446}, {150, 0.0992422}, {100, 0.121567}, {50, 0.186825}} I'm new to Mathematica, and would like ...
2
votes
2answers
339 views
25
votes
4answers
648 views

Enforcing correct variable bindings and avoiding renamings for conflicting variables in nested scoping constructs

Using global variables the following turns an "expression" into a Function: expr = 2 x; Function[x, Evaluate[expr]] Of course ...
9
votes
1answer
440 views

Running .NET/Link on Mono (On MacOS or any UNIX or Linux Distro)

Has anyone have any luck running .NET/Link on Mono? When I run .NET/Link to call Mathematica from within a Mono program, this is the error message I receive. ...
4
votes
1answer
226 views

How to find derivative of a numerical solution, where precision is ambiguous?

I am trying to take the derivative of a numerical solution. I am concerned that the way I'm doing this may be problematic due to numerical error; I think there must be a better way but I'm not very ...
1
vote
3answers
2k views

How do I create a matrix of functions?

I'm trying to create a matrix in which the elements are functions of two variables, but I can't figure out how to do it. Is it possible? The only way I could figure out is to define the matrix in ...
2
votes
1answer
167 views

Expression for the real 7/3 power

I need an expression for the real 7/3 power of a real-valued function, i.e., a reformulation of f[x_] := g[x]^(7/3) that works for negative values of ...
2
votes
1answer
802 views

Variable name string to expression

I'm not sure how to name this problem appropriately. But anyway. I have, say, three variables (arrays in my case), which I call: A1, A2, A3 I would like to ...
0
votes
1answer
111 views

Collecting roots of different equations and create a list

I solve two equations and have two solutions one by each equation. I want to create list of these roots. Could anyone please help me? Appreciate it. m02R150 = FindRoot[P1 == 0, {E1, 0.07, 0.1}] ...
2
votes
1answer
192 views

Executing C programs within mathematica [duplicate]

I have a requirement for executing a C program within Mathematica. The user will provide the inputs and the expected results on a front end. Mathematica runs the C file, obtains the result for the ...
6
votes
2answers
410 views

Variant of the cutting-stock problem in Mathematica

I'm pretty new to Mathematica and am trying to learn to solve problems in a functional way. The problem I was solving was to list the ways in which I could sum elements from a list (with repetitions), ...
0
votes
2answers
777 views

Copy and pasted graphics are fuzzy

I have a function that creates a 2D line with filling to the axis. When I copy this graphic into word it is very fuzzy, so much so that the numbers and text are almost unreadable, not to mention the ...
8
votes
1answer
356 views

How to remove some elements in a list based on a rule?

I want to deal with the following list. mylist = Table[cof[i] exp[i], {i, 1, n}]; (*n is very larege *) exp[ ] is a function ...
13
votes
3answers
338 views

Question about using a pattern in ReplacePart

I noticed that "ReplacePart" can use pattern. For example: ReplacePart[{{0, 0, 0}, {0, 0, 0}, {0, 0, 0}}, {i_, i_} -> x] {{x, 0, 0}, {0, x, 0}, {0, 0, x}} So ...
4
votes
2answers
277 views

Extracting data from a table under conditions

I have a very large table with two columns. Let's say the name of first column is E and the name of the second is P. How can I get the E values when P = 0.
16
votes
1answer
2k views

2D Heat equation: inconsistent boundary and initial conditions

I'm attempting to use NDSolve on a 2D boundary value problem with initial conditions. Upon running my code, I get the following message: "NDSolve::ibcinc: Warning: Boundary and initial conditions are ...
9
votes
1answer
695 views

Filling only when one curve is below the other

I want to fill the area between two curves only when curve-1 (Black) is below curve-2(Blue). So In this example, I don't want the middle portion shaded but just the left and right tails to be shaded. ...
6
votes
3answers
1k views

Keep function range as a variable

Plot[2*x^2 - x + 2, {x, -1, 1}] plots a function of x from -1 to 1. As far as I can see, I cannot "save" this range in a variable: ...
9
votes
3answers
618 views

How do I get a two-term polynomial with a leading negative sign to display in the correct (i.e. textbook) order?

The first three expressions evaluate as expected and the polynomial is displayed in what I would call "textbook" form. The last expression, however, switches the order of terms. Mathematica employs ...
7
votes
3answers
490 views

Efficient way to utilise Parallel features to make use of many cores

Let's say I have 100 cores/kernels as my disposal and want to compute a function of two variables f[x,y] over {x,1,10}, ...
3
votes
1answer
118 views

Stop TradtionalForm evaluating expression

I'm trying to get this expression to display as typed instead of evaluating the 1/1.121. ...
0
votes
1answer
89 views

Formatting Equation Output Neatly

I looked around and couldn't find the answer to this anywhere, so I'm sorry if this is a bad question - I'm pretty new to mathematica. I wrote a program to help me compute some annoying series ...
1
vote
1answer
90 views

Calibrating Precision in calculations

As the title says, I encounter an irritating problem which has to do with the accuracy or the precision used in the calculations. To be more specific, I have the following code: ...
6
votes
1answer
702 views

Octonions in Mathematica

Is there a package or Notebook for Mathematica that can enable me to do some numerical calculations with octonions? Maybe a way to plug-in the octonion multiplication table?
4
votes
1answer
173 views

How to programatically save a notebook created by CreateDocument

I've already written code that generates about 20 notebooks using "CreateDocument" and I was wondering if there exists a method to automatically save them. Is there an easy way to create a notebook ...
4
votes
1answer
504 views

A Faster way to combine two Lists of different structures into one of a different structure [duplicate]

I have the following two lists (each containing over 500,000 elements). Here is a sample: ...
29
votes
5answers
1k views

Voronoi diagrams for generators other than points

Any suggestions how to determine Voronoi diagram for sites other than points, as e.g. in the picture below? Input is a raster image.
1
vote
1answer
526 views

Forcing evaluation of ArgMax

How to force evaluation of ArgMax before its output gets used in Solve? Background: I'm trying to solve for the Nash ...
0
votes
2answers
227 views

Why does ; suppress Dynamic output? [duplicate]

Dynamic[x=7]; does not make x dynamic! But Dynamic[x=7;] makes ...
16
votes
1answer
347 views

How does the built-in debugger decide what to highlight?

How does the built-in debugger decide which definition to highlight in the notebook when Break on messages" is enabled? Here's an example to illustrate what I mean. First, enable the debugger ...
8
votes
2answers
333 views

What is the value Re[Sqrt[1+I*2*x]]?

When I try to evaluate Re[Sqrt[z]], for some values of Mathematica fails to evaluate it. For example, Re[Sqrt[2 + I*x]]` ...
2
votes
1answer
251 views

Color coding based on 4D data within a building

I am trying to create something similar to a Heatmap within a building. Suppose I have a room with dimensions, {30,40,50} as length, width, and height respectively. I have a set of data that is of ...
0
votes
1answer
205 views

ContourPlot of a complicated function

I have the function $pot_1(x,y,z)$ which is given in analytical form. So, in order to plot the contours at the primary planes $(x,y)$, $(x,z)$ and $(y,z)$, I use the following ...
6
votes
1answer
353 views

Why does compiling a function with ConstantArray give an error when used in parallel?

Here is a sample compiled function: ...
3
votes
1answer
245 views

ConditionalEntropy and Statistics`Library`NConditionalEntropy

There is a function available from the Statistics`Library context called NConditionalEntropy that appears to compute ConditionalEntropy. Thus ... ...
2
votes
1answer
414 views

Solving an equation involving a determinant

I have a matrix which doesn't include numerical values. There are four variables in it. It is defined by ...
7
votes
3answers
1k views

Custom mesh in ListPlot3D

I have the following data: ...
4
votes
0answers
119 views

Proper treatment of roots and powers in Series?

I have the following problem in Mathematica 9 on Linux. I let Mathematica compute the Series expansion: ...
1
vote
1answer
399 views

How do I draw multiple 3D shapes defined by lists of points?

I'm attempting to draw $N$ cones on a 3D object, where each cone is specified by a pair of 3D coordinates. The first coordinate is for the cone's base, the second one for the cone's apex. Here, I ...
3
votes
1answer
570 views

NonlinearModelFit returning nonsense for very simple data

In fitting the following data, if I first log transform the y-values and use LinearModelFit I get a set of parameters that fits the data: ...
2
votes
1answer
351 views

Evaluate Numerator and Denominator Separately

I have this function. ...
6
votes
1answer
146 views

How can I keep a plot's filled area from obstructing other lines when exported as EPS?

I am plotting several functions, some of which have fillings. After I combine all the functions together on a plot and export the plot to an EPS file, the fillings obstruct other lines. Exported PDF ...
7
votes
2answers
108 views

Erfc Not Returning Results Specified in Documentation

In the documentation for Erfc (under "Possible Issues"), the following command returns a number that is extremely close to 2: However, when I run this same command in a fresh kernel, I get: ...
3
votes
1answer
953 views

Error message from evaluating NonlinearModelFit

I am trying to fit data to a Morse potential using NonlinearModelFit as follows: ...
-4
votes
4answers
2k views

Piecewise linear Interpolation between data points [closed]

Is there some sort of functionality built into Mathematica that will let me linearly interpolate between (x, y) pairs of data in an array? Example: I have the two points (1, 10) and (2, 20), how can ...
11
votes
2answers
624 views

Finding the perimeter, area and number of sides of a Voronoi cell

Does anyone have any suggestions how to determine the perimeter, area and number of sides of each Voronoi cell in Voronoi diagram?

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