6
votes
2answers
2k views

Error entering equation in DSolve

I entered a command incorrectly as follows: DSolve[{y'[x]=y[x]},y[x],x] I am now experiencing: ...
4
votes
1answer
874 views

Why does piecewise plot have a discontinuity when the function, first and second derivatives are equal?

There were some related questions to this one, but in this case we have the function value, the first derivative and the second derivative all equal (that was actually the problem I was solving). We ...
0
votes
2answers
219 views

Hide function arguments (from unknown functions) for simpler output [duplicate]

How can I print my expression with my function's arguments hidden? For example: exp=A[r,z]+B[s]^2; HideArgs[exp] Output: ...
1
vote
1answer
93 views

Circumventing the default scoping: Assign a variable inside a function [duplicate]

I'm currently trying very hard to assign a variable inside a function. Therefore I'm using a function like this, which should reassign a predefined variable. ...
3
votes
1answer
226 views

Ugly plots when printing notebook to pdf

One image is worth one thousand words, so: Question: At what options should I be looking, so that what I see in my notebook is what I get in my printed pdf ? Here is the code I'm using: ...
1
vote
1answer
144 views

Possibility of evaluating the expression within a NestList at each iteration?

I want to rotate iteratively a triangle about the same point, increasing for each iteration the length of its side in the same proportion and change the color of its sides. I came up with the solution ...
9
votes
1answer
262 views

User-defined usage message template; removing repeated text

In Mathematica 9.0.1, I want to write a user-defined template for a function that I wrote: myfunc ...
4
votes
4answers
372 views

Using Locators in a non-standard Manipulate code

I'm trying to adapt Nasser's method for using a control variable inside Manipulate to selectively choose what part of the code should be recalculated depending on the controls changed (see this ...
0
votes
0answers
366 views

Unable to Solve Two-Point Boundary Value Problem

I'm trying to solve the equation -u''[x] + ((x - k)^2 - en[x]) u[x] == 0 using the boundary conditions ...
1
vote
1answer
243 views

Using Manipulate with a control variable for selective recalculation

I'm trying to adapt Nasser's method for using a control variable inside Manipulate to selectively choose what part of the code should be recalculated depending on the controls changed. I've also read ...
4
votes
2answers
451 views

Using units and piecewise functions in Integrate

For simple cases, Quantities appear to be handled well by Integrate: ...
2
votes
2answers
519 views

DensityPlot Increase Information

I am trying to make a density plot in Mathematica, however the distribution of the plot is not as visible as I would like. I plotted the same function in python and it contains a greater visible range ...
2
votes
2answers
1k views

Trying to graph trajectory function in Mathematica? Won't Graph?

The exercise is: Define the trajectory function y(x) in Mathematica. Pick the initial speed (in meters per second) equal to ...
1
vote
1answer
112 views

Simplifying using assumptions

Is there a way to simplify the following equation (-p(a-x)((a-b)P(b-x)+Q(b+x)(a-b+2x))+q(a+x)(-(a-b)Q(b+x)+P(b-x)(-a +b+2x)))/((b-x)(-a + x)(a+x)(b+x)) assuming ...
4
votes
4answers
2k views

List manipulation: position & max value combination

Starting with {{0, 0, 0}, {1, 1, 2}, {2, 3, 3}, {3, 4, 5}} I would like to get {{0, 2, 3, 5}, {1, 3, 2, 3}} where the ...
1
vote
1answer
317 views

MapThread multiple functions onto multiple lists

I'm trying to learn the functional style which seems to prevail in Mathematica. I'm having trouble accomplishing the following: Let's say I have multiple lists of arbitrary data (using two lists ...
2
votes
1answer
332 views

How to make a big image/dashboard containing various data-graph

I want to make and image/dashborad (to export to PDF) with many VERTICAL bullet graphs gauges. And I can´t make it, in a automatic way. In general, the questions are: QUESTION 1: How to make a ...
1
vote
1answer
426 views

Unable to solve a set of equations with Solve

I'm trying to solve the following equation using Mathematica 9.0.1.0 : ...
5
votes
5answers
424 views

Counting 'False' values at the ends of a list

I have table like this: t = {False, False, False, 4.5, 6.789, 1.23, 0.98, False, False} and I want to know how many False values I have at the beginning and at ...
1
vote
1answer
128 views

Reflecting the Polya-Aeppli distribution

How would I go about reflecting the Polya-Aeppli distribution in Mathematica about a y-axis (switching left and right) while keeping the command. The distribution will not allow negative parameters ...
0
votes
1answer
629 views

How to write a variable in terms of the other [duplicate]

I have an equation that defines a variable like y=4x+a. I had another equation, z=x+2+4, I would like to know if there is a way in Mathematica to get an expression in which z= a*y+C, in which a and C ...
11
votes
4answers
775 views

Breaking up long equations in TeXForm

If I have a horrifically long expression and output it to TeX using TeXForm, I get a long equation which needs to be split up into multiple lines. But splitting it up manually can be quite cumbersome. ...
5
votes
0answers
125 views

How to Check Spelling strings written inside input cells

Is it possible to check the spelling of strings? Strings are often used to show messages in my user interfaces, and I would like to have an automatic checking. Methods that export all the strings to ...
5
votes
2answers
450 views

How to test whether an expression is a valid variable?

I would like to test whether an argument is a valid variable for functions like Solve and DSolve. For instance several ...
0
votes
1answer
193 views

Why BarChart3D plot of Mathematica 9 is not working similar to Mathematica 7 version?

Mathematica 7 Needs["BarCharts`"] BarChart3D[{{1, 6, 8}, {2, 7, 1}, {3, 1, 4}}] While in Mathematica 9 it is not plotting in this manner. Please help me to ...
5
votes
2answers
349 views

Replace rule with function? Derivatives don't evaluate

Say I have an expression (call it expr) involving a function, f[x]. I'd like to be able to evaluate that for a particular choice of ...
2
votes
1answer
154 views

How to break graph to fill in the gap in pdf

I've printed my notebook into a pdf. There is a huge gap in the left page, due to the fact that the graph in the right page isn't divided to fill in the gap. Is there a way to fix it, preferably ...
2
votes
1answer
122 views

Strange results of definitions using OwnValues

I am asking this question simultatenously with this one, which is strongly related. I was trying to see if I could create the behaviour as in that question without using ...
10
votes
2answers
303 views

Another difference between Set and Setdelayed. Evaluation shortcut?

A little while ago I wondered why f[x_] = f[x] gives an infinite iteration. I ended up discovering the following difference in evaluation between ...
6
votes
1answer
144 views

Graphics Function Definition Style (Using SubValues vs. DownValues)

I am going through some of the items in "Modern Differential Geometry of Curves and Surfaces with Mathematica, Third Edition". An example of the style used by these authors is: ...
2
votes
1answer
175 views

Using DeleteCases with multiple AstronomicalData properties

I am attempting to use AstronomicalData and DeleteCases together to remove invalid cases of two properties while listing the ...
4
votes
4answers
978 views

Replace symbols with values without evaluation

If I have assigned values to a, b and c: ...
2
votes
1answer
208 views

Simplify equation using conditions/inequalities

If I have an equation like f[x](1 + a)==0 I'd like to be able to tell Mathematica that 1+a doesn't vanish in general, and get back ...
22
votes
4answers
822 views

Arbitrary precision spline interpolation

The current implementation of Interpolation does not allow arbitrary precision spline interpolation. Yu-Sung Chang says here that "it is not hard to implement it ...
0
votes
0answers
66 views

Display functions without dependence?

I'm solving systems of equations with a few different functions of time, t, and so I'm getting output with lots of [t] running around. Is there a way to display these functions without the ...
1
vote
0answers
28 views

Possible bug while plotting homographic function with stylled axes (?!) [duplicate]

Seems like a bug to me, don't have time to dig more now. WinXP V9.0.1.0 ...
1
vote
2answers
131 views

Computing lists using AstronomicalData

Edit: Initially in my question I asked how I could search the database of AstronomicalData["Exoplanets"] and return 2 filtered values that only contained valued ...
1
vote
1answer
870 views

Fourier Series of “Split” Defined Function

Not sure how to phrase this in a concise way, anyway it seems like the function FourierSeries assumes the interval for which to compute the Fourier coefficients of a given function is $[-\pi,\pi]$, ...
1
vote
1answer
299 views

Filling only part of a plot [duplicate]

I have something plotted on [-6,6] but I would like to fill only the part from [-5,5] (to the axis). I'm looking through the documentation but I'm not terribly well-versed in Mathematica and can't ...
3
votes
2answers
348 views

Draw only part of axis in graph

I'm looking to draw only one half of an axis in ContourPlot3D, mainly because I don't wan't the axis lines to be where the interesting stuff happens (intersection ...
4
votes
2answers
283 views

Graphing convolutions of user defined functions

I am a statistician who is very new to Mathematica. Ultimately I would like to be able to graph convolutions of arbitrary user defined functions. But I can't as yet obtain values of such ...
10
votes
3answers
2k views

help to plot Poincaré section for double pendulum

I am reading a book about classical mechanics. In the chapter about chaos, it gives the simplified and scaled equations for double pendulum as $$ \frac{d}{dt}\left[ \begin{matrix} \alpha \\[3mm] ...
0
votes
2answers
1k views

Defining a function in terms of matrix elements

Currently trying to use elements from a matrix in defining a function however having some trouble. This is a somewhat simplified version of the problem. Say I have the matrix ...
5
votes
2answers
499 views

Can I frame text in a plot to look like legend?

I have a DateListPlot, much the same as below, that I want to overlay text onto. I'd like the text to be wrapped in a frame much the same way as the legend box is, ...
3
votes
1answer
72 views

Replacing multiple instances of a symbol with different variables and assignments

I have an expression of the form: expr=x+y+n+Sin[n]+n^2 I would like to replace each of the variables n with a different ...
0
votes
0answers
220 views

Differential equation with random variable

How can I derive analytically or compute numerically the solution to following differential equation $$ dy/dt = y\cdot X\cdot (y\cdot X - g(y,X))\cdot X $$ where X is a random variable (e.g. from a ...
0
votes
2answers
178 views

Associate the elements of a table

I have a table form as: table = {{a, 6}, {b, ff}, {c, 2}} I want to associate the first element of each pair from the table to the second element of the pair as ...
1
vote
0answers
77 views

Extract information from functions that returns nested structures with DefineDLLFunction

Where can I find examples devoted to extracting information from functions that returns nested structures with DefineDLLFunction in Mathematica? The only example I found and understood, was given by ...
2
votes
0answers
153 views

Calling Mathematica from Lazarus/Freepascal

I will appreciate if anyone can give me an hint about freepascal and mathematica mathlink communication. I'd like to build a Form using Lazarus/freepascal that call mathkernel. I'm trying to move ...
3
votes
1answer
97 views

some confusion about ReplaceRepeated

This is Right. NestWhile[Log, 100, # > 1 &] {100} //. {x_} /; x > 1 :> {Log[x]} 100. //. x_ /; x > 1 :> Log[x] This is wrong,why? ...

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