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3
votes
1answer
113 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
358 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
289 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
120 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 ...
2
votes
0answers
190 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
119 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? ...
0
votes
1answer
141 views

Showing result of derivative and other functions [closed]

I have a problem with my Mathematica 7.0 When I write: Derivative[x^2, x] Mathematica returns as result : Derivative[x^2, x] ...
17
votes
2answers
2k views

Why do certain values in ArcSin not fully evaluate?

This is a continuation of: Why do certain fractional values in TriangleWave not evaluate? The analysis by R.M and rasher revealed that problem to reduce to the behavior of: ...
6
votes
1answer
144 views

Issues with $MachineEpsilon

I'm attempting to add $MachineEpsilon to numbers I am pulling from the domains of 3 interpolating functions. I pulled 3 numbers, and for one of these numbers adding ...
1
vote
1answer
110 views

storing rescaled images in new variables

I'm trying to assign random image files that undergo rescaling to a list of variable names. The images I'm trying to assign are the result of mapping the ImageResize function of two arguments to the ...
6
votes
1answer
138 views

Why do certain fractional values in TriangleWave not evaluate?

Bug introduced in 8.0 or earlier and persisting through 11.0.1 or later While answering another question I discovered that TriangleWave does not automatically ...
9
votes
2answers
423 views

How to avoid an expensive subset of a Manipulate computation when dependent variables have not changed?

I have a Manipulate where a portion of the calculation that ends up displayed is dependent on a subset of the Manipulate control ...
2
votes
2answers
183 views

ListPlot : range from $0$

I want to plot values of a table for example: table = {0.456, 0.7899, 1.3456, 9.8908} But I want to Plot points (x,y) like: ...
0
votes
0answers
28 views

Incorporating Built-In Function Options/Parameters into Shorthand [duplicate]

Shorthand syntax provides an alternate way to apply functions and, in many cases, improves readability. A simple example would be ...
2
votes
0answers
91 views

Limit[Sum[(2*E*n)^w/(w^(n/2+w)), {w,2,n}],n->Infinity]

I would like to show that the following (and other similar formulae) tends to zero. Limit[Sum[(2*E*n)^w/(w^(n/2+w)), {w,2,n}],n->Infinity] What's the right ...
-2
votes
1answer
149 views

Adding a textfield to the function that I implemented

Adding a textfield to the function that I implemented to represent the tangent or derivative of a function, but I've added so mark errors. ...
0
votes
0answers
29 views

Threading a single abscissa through a list of ordinates [duplicate]

Suppose that I have the following list, called list. list contains elements X, ...
2
votes
2answers
1k views

Expansion with binomial coefficients

How can I get binomial coefficients in expansion of $(n x+i) (1+i x)^n+(n x-i) (1-i x)^n$, where $i=\sqrt{-1}$ and $n$ is an integer. I have no idea how to coax Mathematica to do something remotely ...
4
votes
2answers
1k views

How to make slider in/visible in Manipulate?

I need your help with making a slider invisible and visible in a Manipulate. Here is my code: ...
0
votes
1answer
177 views

Replacing character in position

I'm trying to use Mathematica to make some work on binary data, and I'm missing something. Consider the string "111". I want to flip the last bit to become ...
0
votes
1answer
67 views

Is it possible to modify the options for a particular cell from another cell? [duplicate]

I was wondering if I can toggle the "CellOpen" state from a cell (or bunch of cells) from another cell. i.e. I am imagining having a manipulate command along the lines of: ...
1
vote
2answers
413 views

NDSolve boundary query / Extracting values from solution

I have a function $O_{2}$ with boundary conditions $O_{2}(r_{o}) = p_{o} $ and $O_{2}(g) = O_{2}'(g) = 0$. I plot it using the solver code below; ...
0
votes
3answers
196 views

Partial products in prime steps [duplicate]

I am trying to find out partial products going up in prime steps for Euler's product formula $$\prod_{p} \frac{1}{1-p^{-s}}$$ Trying things like ...
0
votes
1answer
330 views

Is linear interpolation applicable here

From my understanding about Linear Interpolation especially of that of Newton's Divided Difference Polynomial, we could get the value of F(x) from the given set of ...
3
votes
2answers
419 views

Evaluate in Plot leads to function error

Please help - I'm really struggling to understand why this evaluates with errors. ...
0
votes
1answer
148 views

Extend a function defined for integers to a differentiable function of a real variable

Here is a function that calculates the probability of randomly landing on a Fibonacci number not greater than $n$: ...
2
votes
4answers
1k views

How to set magnification of image to 75%

Right click on an output image, choose magnification. There are 25%, 50%, 100% etc. But how can I set to 75%?
1
vote
2answers
344 views

Find the centre of FindGeometricTransform

I'm interested in using Solve[] to find the centre point of rotation (as an $x,y,z$ coordinate point) and axis of rotation (as a vector) from a ...
2
votes
1answer
2k views

Fitting data using a differential equation

I have data generated from two functions given below. How can I go about finding a fit of the form: y'[x] == -(a + b/(c + d y[x] + e F[x] )) where a,b,c,d,e are ...
0
votes
1answer
87 views

Mapping a function of two arguments where the 2nd arg has a fixed value

I create three random images: i1 = Image[RandomReal[1, {8, 12, 3}]]; i2 = Image[RandomReal[1, {8, 12, 3}]]; i3 = Image[RandomReal[1, {8, 12, 3}]]; I can scale a ...
6
votes
1answer
376 views

How can I define a ⊕ operator?

What is wrong with the following code? CirclePlus := SparseArray[Band[{1, 1}] -> {##}] & a_ ⊕ b_ := CirclePlus[a, b] SetDelayed::write: Tag Function in (...
0
votes
1answer
112 views

Solving polynomial equations takes infinit time

I need to solve an polynimial equation, but when i try to use Solve or NSolve in mathematica, its cant find the solution in appropriate time (i interrupted calculation after 5 hour left). The ...
0
votes
3answers
377 views

Solving algebraic equations

How may I make n and k in terms of x and y in this ...
0
votes
0answers
24 views

Evaluating a String that is a Variable [duplicate]

I have a Variable assigned a value, say ImportantDocuments=1 How do I make N["ImportantDocuments"] evaluate to be 1 instead of ImportantDocuments I found that N[ToExpression["...
6
votes
2answers
569 views

Passing Mathematica function via MathLink or LibraryLink to c (or c++)

I want to numerically solve the heat equation. To do so I wrote a program in C++ - It is a BVP $(\alpha T +\kappa \frac{\partial T}{\partial r}=f(t))$, where $f(t)$ is an arbitrary function, whose ...
0
votes
1answer
258 views

Why isn't Simplify completely simplifying my expression when it has all the necessary info?

I have a complex variable, and I'm trying to multiply it by its Conjugate[], which should give me a real number. So, I'm currently doing: ...
1
vote
3answers
1k views

Swap first and last names in a list

Edited to fix an inconsistency in the given example data format. I'm trying to write a simple function to load in a csv list of names which is formatted as "Lastname Firstname Initial " and ...
0
votes
1answer
245 views

PixelValue with pixel indices [duplicate]

How Can we use PixelValue with pixel indices?
24
votes
3answers
608 views

Why x = x doesn't cause an infinite loop, but f[x_] := f[x] does?

If I execute: In[1] := x = x Out[1] = x and then I evaluate the symbol x: ...
2
votes
2answers
1k views

Conditional range in a parametric plot

I have a program that needs to be done like this: ParametricPlot[ equation, If[x < 1, {x, 0, t}, {x, t, 2}]] But Mathematica didn't seem to recognize the ...
5
votes
2answers
255 views

Reduce with Integer domain, but receive a rational solution

Bug introduced in 6.0 and fixed in 10.0 I want to find the integer values $k$ so that D[f[x], x] has integer solutions. I tried ...
6
votes
1answer
627 views

Converting StringForm output to a string produces unexpected results

I want to compose a string that contains newlines, so I tried the following: ...
2
votes
1answer
149 views

How would I get the best quality plot into a TeX editor which includes the legends?

I have currently used "Save Selection As" after highlighting the graph and legend and then saved it as a PNG file, but the quality isn't brilliant. I am using TeXworks on Windows 7. The "Copy As LaTeX"...
0
votes
0answers
308 views

Scroll bar glitch when entering full screen mode at magnifications higher than 100%

I noticed that when I enter full-screen mode in Mathematica 9 (F12 for Windows) using a magnification of 125% (or any other number higher than 100%) there is a horizontal scroll bar at the bottom of ...
0
votes
1answer
159 views

Export/Copy + Paste a plot from Mathematica Trial Version to TeX editor

I wish to get a view plots from Mathematica trial version into a TeX editor, but cannot seem to do it (unless I print the screen and crop the image which leads to bad quality). Is there a way in which ...
5
votes
3answers
619 views

Determing two Nonlinear model fits with 95% confidence bands from one data set

I have the following data which is postulated to have contributions from two different sources .....as can be seen from the confidence band, many points are out of the band. Question: How can I ...
1
vote
2answers
487 views

FindMinimum gets confused by If[…]

I'm confused by why the following doesn't work. I'm trying to numerically minimize a function that has an If statement in its definition, as follows: ...
9
votes
1answer
332 views

Forcing Mathematica to recognize a symbol without defining it

In the Mathematica front-end, symbols that have been defined are colored black and symbols with no definition associated are colored blue. This is useful to prevent spelling mistakes. Also, defined ...
1
vote
2answers
538 views

How can I get an approximate contour plot from a 3D plot?

I have some larger square, Hermitian matrices, M, (dimension 20, say, much more than 4) with 2 independent variables, call them x and y. I can plot the eigenvalues as functions of x and y with: <...
2
votes
2answers
1k views

Processing all files in a folder automatically

I have a lot of files in a folder that needs to be process through a function that I have written in Mathematica. I need help writing a code that would process all the files automatically. ...

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