1
vote
1answer
110 views

Using Mathematica to find Derivatives

I am given a system first order differential equations: $x'=y$ and $y'=6x^2-a/2$, where $a$ is a constant and $'$ denotes $t$-derivatives. I then make the substitution $(x,y)=(x_1y_1,y_1)$. This ...
1
vote
2answers
107 views

Problem evaluating a complicated integral

Apologies for stating my problem poorly in the first instance, thank you for the help in narrowing down the issue. Problem For those interested, it's for the exact unbiased inverse of the ...
3
votes
5answers
136 views

Using Mathematica to find a Derivative

I am given a system first order differential equations: $x'=y$ and $y'=6x^2-a/2$, where $a$ is a constant and $'$ denotes $t$-derivatives. I then make the substitution $(x,y)=(x_1y_1,y_1)$. This ...
0
votes
1answer
141 views

Graphics // Triangle // Manipulation

I have been Mathematica user for a considerably short while. I have learned some of its functionality using wolfram how-to resources and the documentation. I am having difficulties constructing ...
10
votes
8answers
1k views

Finding maximum or minimum of implicit functions

is there any built in function that can be used to find maximum or minimum of implicit functions? For example, if we have the equation $$x^2 + y^2 = (2 x^2 + 2 y^2 - x)^2,$$ then we can visualize the ...
1
vote
1answer
216 views

FindRoot with vector functions

I'm trying to solve a system of non-linear equations with FindRoot, and I get the answer, but also a ...
3
votes
2answers
392 views

How to speed up minimization of function

I have the fallowing code (the functions within that code are replaced by simpler ones, but the code structure is identical): $$$$ ...
13
votes
4answers
2k views

How to implement Donald Knuth's up-arrow notation

How does one enter very large numbers in up-arrow notation? Up-arrow notation was created by Donald Knuth to write very large numbers in it iterated exponentiation form, for example 6↑↑3 = 6^6^6.
4
votes
4answers
704 views

An easier way to find the properties of an ellipse from its equation?

In this Q&A about fitting an ellipse to a set of points, there are multiple answers that generated general equations of the ellipse, like this one by @ubpdqn: However, the steps to find out the ...
2
votes
0answers
124 views

How to specify the time variable for NDSolve

I recall that it is possible to specify which independent variable is the "time" variable in NDSolve, but I can't find it documented anywhere. Does anyone recall ...
1
vote
0answers
103 views

Speeding up the numerical integration of a certain function

I'm using the following function f[t_] := 3/4 t^-3 NIntegrate[(x^4*Csch[x/2]^2), {x, 0, t}, Method -> {Automatic, "SymbolicProcessing" -> 0}]; I ...
0
votes
0answers
66 views

Using less memory to store and manipulate specific types

Is there a simple way to use Integer types (in particular, a table of Integer types) that require only 4 or 8 bytes (reps. 32 and 64 bits) representation? It seems that integers in Mathematica have a ...
1
vote
1answer
84 views

Why does one Monitor expression work while another fails?

I have a (somewhat involved) function f[x?NumericQ, y?NumericQ] and for some reason it behaves differently when given a Table ...
1
vote
1answer
153 views

plotting 3d points: z-axis is squashed

I am plotting 3D points and it occurs to me that Mathematica doesn't have an easy way to specify my points to be plotted in a uniformly scaled cartesian space. For example I plotted ...
1
vote
2answers
99 views

Using AddTo in a function

I want to create a function that will take a variable $x$ and reassign the value $x+2$ to $x$. So f[x_]:= x += 2 However: ...
6
votes
3answers
228 views

Converting expressions to “edges” for use in TreePlot, Graph

This question is similar to this: Nested list to graph. How to "flatten" an arbitrary expression, eg expr = a[b[c, d[e][f], g], h] to a list of key-value pairs ...
2
votes
0answers
102 views

Which functions automatically generate new functions?

In his video http://www.wolfram.com/broadcast/video.php?channel=362&video=1643, Wolfram gives the following example: the output from ...
1
vote
3answers
171 views

Binning events with weights

I have two vectors, one containing sampled energies and the other one for each of these energies a weight: e(i) and w(i). I ...
3
votes
4answers
508 views

How to find a path that traverses each edge of a graph exactly twice?

I have a question regarding a graph traversal problem. This is the graph I am working with: ...
0
votes
1answer
98 views

How to get correct numerical integration which should be zero? [duplicate]

I want to numerically integrate function berrycur over kx and ky. The definition of berrycur is given at the end of the ...
0
votes
2answers
79 views

Convert an expression from one form to another

I have this expression -0.433284-0.758719 x+0.00289158 x^2-0.443672 y+0.00149027 y^2 I want to express it in terms of ...
0
votes
1answer
68 views

strange result with trigonometric triple integral [duplicate]

I'm defining functions e[k_, t_] := Cos[Pi (k - 1) t] cosIntRaw[k_, l_, m_] := Integrate[e[k, t] e[l, t] e[m, t], {t, 0, 1}] cosInt[k_, l_, m_] := Assuming[Element[{k, l, m}, ...
0
votes
1answer
101 views

Probability Distribution of a Multivariate Hypergeometric distribution and maximum probability

Hello to all Mathematica Users! I have this question: Consider a box which contains 69 balls. 17 red, 1 white, 29 blue and 22 green balls. There will be picked 7 balls randomly, without putting the ...
2
votes
2answers
234 views

Delete pairs from a list

I have a data set in which I need to remove all matched pairs of entries - not just the first entry that is duplicated but both entries. To add to the complexity, the pairs must be between different ...
2
votes
2answers
97 views

Funny behavior of Ellipsoid function

From its description I thought that the normalizations of the directions d_i of the semi-axes did not matter when using the ...
5
votes
2answers
310 views

Why doesn't Roots work on a certain quartic polynomial equation?

In everything that follows I am using Roots to get the solutions to the equations. I start off with this equation: $$ \frac{A}{3}x^4 - x^2 + 2ax - b^2 = 0$$ Now ...
0
votes
1answer
48 views

How to check the decimal accuracy of result? [duplicate]

I am trying to check if the result is enough accurate to use. I need an accuracy of 10^-6 from some numerical method. Something like root finding algorithm. But how do I check that in mathematica? I ...
0
votes
0answers
27 views

Clear variables [duplicate]

I'm new in Mathematica and I am working with various notebooks. My problem is that when I run a notebook, it seems taking definitions from the previous notebook. For example in 'notebook1' I make an ...
1
vote
1answer
124 views

Unexpected result from FullSimplify

In the following simplification why doesn't Mathematica get a zero when asked to compute "Y-Z" eventually? ...
6
votes
3answers
261 views

String templating

I am pretty new to string processing in Mathematica. But I'm having some problems in doing simple string template filling to my mind elegantly. For example when doing export for my answer here, one of ...
10
votes
9answers
991 views

How can a power of 0 or 1 be replaced?

Consider this given example for ReplaceAll 1 + x^2 + x^4 /. x^p_ -> f[p] This returns ...
1
vote
2answers
109 views

How can I speed up the export of graphs in DIMACS format?

I'm creating random graphs with suitable properties and exporting them in the DIMACS format. Already, for rather small graphs with, say, ~60k vertices and ~240k edges, ...
1
vote
1answer
161 views

Factoring terms out of a polynomial

I don't do much algebra in Mathematica and was surprised to discover, while attempting to answer this question, that I had no idea how to factor out an expression from a polynomial. The question was, ...
5
votes
2answers
296 views

How to color separate a colored-in-pencil drawing?

I'd like to pick out just the "pencil" color in some drawings done by a young member of the household (he'd like to print out copies of these pictures and distribute them to his class mates on the ...
3
votes
1answer
89 views

Symbolic Output after numerical computation

I have a small question about the symbolic output. I started to write a program that generates the coordinates of n-dimensional polytopes by Wythoff construction. For crystallographic groups, all is ...
3
votes
3answers
245 views

How to use LineLegend and SwatchLegend together

I am wondering if one can place on the right of the plot frame a single legend that is a combination of a LineLegend and a SwatchLegend. What I want is to see the line with its label on top of the ...
11
votes
4answers
791 views

Is there a way to increase the smoothness of a cylinder?

I am using Cylinder to produce wide flat disks (in Mathematica 8). This works just fine except that the circular base of such a cylinder turns out to be really just ...
5
votes
1answer
231 views

More efficient Omnibus number determination?

Amusing myself with concepts from "Omnibus Sequences, Coupon Collection, and Missing Word Counts", in particular the sequences. To paraphrase the concept, a string is k-Omni over some alphabet a if ...
2
votes
1answer
61 views

How to joint symbolic expressions together [duplicate]

I want to joint symbolic expressions together to create a another symbolic expressions. one way to do that is as follows: ...
0
votes
0answers
97 views

A derivative encountered in matrix factorization using gradient descent

I want to factorize a matrix $a_{ij}$ as $$ a_{ij} = \sum_k u_{ik} v_{jk} $$ using variational method for some reason. That is, I want to minimize the cost function $$ F = \sum_{ij} b_{ij}^2 $$ with ...
0
votes
1answer
135 views

Why does show combined plots and graphics fail in CDF Player but not in Mathematica?

The question is, how might I get the following script working as a CDF demo of complex inversion in a circle? It works fine in my home edition of MMA 8 run on OS X Mavericks. When saved as a CDF file ...
6
votes
3answers
185 views

Circumnavigating a curve or going through it to show different behavior

I am not sure if what I want to do is possible in Mathematica. I've provided something simple below to convey what I want to do. Basically what I want to happen is that when the ...
2
votes
2answers
84 views

Using Table with arbitrary number of variables [duplicate]

Let $P=\{p_1,...p_n\}$. I would like a way to implent Table[Expression,{$p_1$,lim},{$p_2$,lim},...,{$p_n$,lim}] where n and lim are parameters defined by the user. Any ideas?
0
votes
1answer
73 views

Finding the right DeleteCases pattern for <<199>>

I have a list in Mathematica with several items like <<199>> and <<104>>, I would like to get rid of them using DeleteCases, but none of the patterns I ...
5
votes
2answers
117 views

Comparison Operation for Nested Matrices

I have a nested matrix n as bellow ...
4
votes
2answers
152 views

After executing MessageDialog[] how can I wait for it to close before continuing

After executing MessageDialog[] how can I wait for it to close before continuing? I want to popup up a message and wait for the user to hit OK before continuing. Is there a mechanism for this?
0
votes
1answer
886 views

wolfram mathematica intersection of two surfaces [duplicate]

I use wolfram mathematica. There is a function of two variables which defines the surface z = f(x,y), the second surface is defined as z = const. How to find the line of intersection of these two ...
2
votes
2answers
88 views

Creating function with matrix argument

I am completely new to programming, so I apologize in advance for a stupid question. I want to program an algorithm for computing invariant factors of a finitely generated abelian group, so in ...
4
votes
4answers
282 views

Defining a pure function involving a function argument

I've got an expression involving x and y that I want to use as a MeshFunction: ...

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