14
votes
4answers
972 views

Strategies for avoiding and handling shadowing

When dealing with namespaces in Mathematica (BeginPackage, $ContextPath ...) one is unavoidably confronted with the problem of ...
13
votes
2answers
377 views

How to speed up the plotting of B-spline curve?

Three months ago, I asked a quesion about B-Spline basis function here, Today, I used this function to plot B-spline curve. The definition of $N_{i,p}$ ...
11
votes
3answers
4k views

Simplify expressions with Log

How can I get Mathematica to simplify the following expression n Log[a] + m Log[b] - m Log[a + b] - n Log[a + b] into ...
11
votes
2answers
3k views

FindFit returns worse result when putting constraints on parameters

I want to fit some data to a model of exponential decay using the FindFit function: ...
11
votes
1answer
350 views

Why does Assuming[x > 0, TrueQ[x > 0]] return False?

Assuming[x>0,TrueQ[x>0]] should, as I understand it, test TrueQ[x>0] after assuming ...
11
votes
1answer
2k views

Where can I permanently modify $Path?

I've quite forgotten: what file does one modify in order to add directories to $Path globally? Specifically, I want to include ...
10
votes
1answer
284 views

Context of localised (dynamic) symbols

When you localise a symbol with Module, the created unique symbol is usually in the current context. There seems to be an exception to this which has further ...
10
votes
4answers
249 views

Is it possible to separately call the default value of a variable which isn't at the end of the sequence?

After reading this post I recalled an old question I once met. We know that we can set default values for variables of a function: ...
10
votes
6answers
4k views

How do I draw a hemisphere?

I want to draw a solid or partially transparent hemisphere above a partially transparent cuboid object in Graphics3D. However, I do not know how to do this s.t. only half the sphere is drawn. Here's ...
10
votes
3answers
398 views

How to set a TraditionalForm output for a symbol

How do I set a TraditionalForm output for a particular symbol/function? In particular I would like my user-defined symbol ...
10
votes
1answer
3k views

Bifurcation diagrams for multiple equation systems

I am interested in constructing a bifurcation diagram for some of my parameters (especially for β and γ) in the dynamical system given in the code below. I want to see how parameter changes affect the ...
9
votes
2answers
321 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 ...
9
votes
4answers
1k views

How make f[{x,y}] evaluate as f[x,y]? [duplicate]

I frequently encounter the situation where I have a function of two real variables defined, e.g.: f[x_, y_] := 9 - x^2 - y^2 But then I need to feed into ...
9
votes
2answers
370 views

Seeking strategies to deploy a function securely without a front end

Background I have a fuction, which calculates an analytic solution to a multi-dimentional geometry problem. The function takes a list of real numbers (typically less than a dozen) and outputs a ...
9
votes
5answers
795 views

Create filling between two trig functions

Working with trig functions, period, amplitude, etc. I found a worksheet at a calculus website, with some nice questions related to interpreting trig functions, at least, they provide some "fun" ...
8
votes
1answer
692 views

Generating dynamic Inputfields

I want to create a bunch of input fields, four in this case, one for each element of the list "x", but since Dynamic has ...
8
votes
1answer
5k views

Mathematica Bifurcation

Continuing with the same question I have posted earlier I would like to find the equation of the stable fixed point curve using my graph, i.e. from the curve somehow find the equation for $x=f(x)$. I ...
8
votes
1answer
578 views

Exporting a 3D plot into a 3D viewing format and axis scaling

I've been trying to export a Plot3D into an X3D (JVX, VRML) file using the Mathematica's Export function. The problem is that when the PlotRange is large compared to the other two dimensions the ...
7
votes
2answers
1k views

Elegant way to handle columns operations

Inspired by this question from @sjdh and by my recurrent use of columns operations in database sets, I was looking for one way to make columns operations more symetric, so I can handle with matrix and ...
7
votes
4answers
258 views

Are persistent variable values after the kernel is stopped possible?

Is there a way to make values of variables persistent even after the kernel is stopped? Example, if I were to set up a list for which I append new list items (such as a check ledger, as a basic ...
6
votes
1answer
217 views

Precompiling a Whittaker function

Is there a way to speed up the evaluation of special functions in Mathematica? I am particularly interested in the Whittaker W function. For instance, the following piece of code: ...
6
votes
1answer
526 views

How to speed up calculations with large number of replacement rules?

In my program I have an expression which looks like: ...
6
votes
4answers
805 views

Function argument to default under certain condition

Inspired by this and this question (and how I handle this in practice), what is the best way to default a function value when a certain condition is met? For example, if a function is defined as: ...
6
votes
1answer
287 views

Return a Part by Reference? (For accessing hierarchical / structured data)

Is there a way to return a part of a list by reference, for reading and writing? I want to do this so I can easily manipulate "rule-styled structured", i.e., hierarchical data that is loaded from a ...
5
votes
2answers
295 views

Manipulate changing controls

Is it possible to use Manipulate and Switch to change the Manipulate controls? ...
4
votes
3answers
905 views

Simplify function notation

I have some calculations with arbitrary functions. In the output, Mathematica always shows the functions with its arguments. I would like to tidy the notation a bit, by hiding the arguments in the ...
3
votes
5answers
535 views

How to write a function to remove comments from a .m source file preserving formatting such as line wrapping reasonably?

How to write a function to remove comments from a .m source file preserving formatting such as line wrapping reasonably? This means if I have ...
27
votes
1answer
1k views

What is wrong with triangle PlotMarkers in v.10.0.0?

Bug introduced in 10.0.0 and fixed in 10.0.1 In Mathematica 10.0.0 we have built-in graphical triangle PlotMarkers. Let us look closer on them: ...
20
votes
4answers
906 views

Why does Mathematica claim there is no even prime?

I wonder if this is a bug, or if I'm misunderstanding something: Exists[n, EvenQ[n] && PrimeQ[n]] // Resolve (* ==> False *) So if I interpret this ...
19
votes
2answers
317 views

Derivative of a pure function with SlotSequence

I can live with this but I can't figure out why the following is 0: Derivative[1][f[##] &][x] 0 From documentation ...
19
votes
2answers
429 views

Difference between Association and Dispatch

In the example below, Association has a different behavior from Dispatch: ...
19
votes
2answers
375 views

Why doesn't a Composition[] hold its arguments and what can be done about it?

Now that Composition (also RightComposition) has shorthand syntax I am more inclined to use it, however what I feel should be ...
16
votes
3answers
2k views

What is NDSolve`FEM`*?

I stumbled on this: ?"NDSolve`FEM`*" ...
14
votes
2answers
802 views

How to obtain adaptive sampling as in Plot function?

Adaptive sampling in Plot function can capture the oscillation of a function with very few points. How can I get a similar sequence of point pairs without using ...
14
votes
1answer
363 views

Pure function with attributes of arbitrary number of arguments: Is it possible?

Mathematica allows to define pure function, like Function[{a, b},Length[Unevaluated@a]{b}][1+2,2+3] (* ==> {0} *) Pure functions in Mathematica can take an ...
14
votes
4answers
923 views

How to remove ticks?

I wanted to remove the Ticks in my coding but i can't. Here when i try to remove the Ticks the number also gone. I need numbers ...
13
votes
1answer
305 views

Why does partitioning increase Dot execution speed?

I have noticed that multiplying a list of matrices can be significantly sped up by partitioning the list, calculating the product of the partitions matrices, and then multiplying the results. ...
13
votes
3answers
493 views

Collatz optimization

I'm VERY new to Mathematica programming (and by new I mean two days), and was solving Project Euler question 12, which states: Which starting number, under one million, produces the longest ...
13
votes
1answer
868 views

Styling individual bars in a BarChart with grouped data

Consider the following: ...
13
votes
1answer
254 views

Why does a variable become real when using the second argument of Dynamic?

Version 9, on Windows 7. Please compare these 2 very simple examples Manipulate[ x, Row[{Manipulator[Dynamic[x], {0, 10, 1/100}]}], {{x, 1}, None} ] and ...
13
votes
3answers
798 views

Is it possible to insert an animated image into Mathematica notebook?

I find it very convenient to use Mathematica notebooks to organize the codes + results. I was wondering if it is possible to insert an animated image (say an animated gif) in the middle of a ...
12
votes
2answers
1k views

Filtering and Replacing outliers

I have a set of data that measurements of temperature vs time (date). It is easy to realize when the sensor went wrong as one might see a blip on the data. How to teach to Mathematica to: 1) Detect ...
11
votes
2answers
194 views

How can I make a density plot (or contour plot) with an arbitrary nonlinear scale (e.g. arcsinh, log, biexponential)?

I was inspired by this question, which showed how we can apply logarithmic scaling to a density plot. But I'm not always a fan of a logarithmic scale - it tends to overemphasize smaller features. ...
11
votes
3answers
319 views

Why is (-1.)^2. a complex number

Why (-1.)^2. in Mathematica returns a complex number? It looks like in both C and Fortran it returns 1. Why does Mathematica behave differently than the other ...
11
votes
1answer
1k views

How to specify default style in Mathematica 9

In Mathematica 8, I can use GraphicsBoxOptions->{DefaultBaseStyle->{"Graphics", FontFamily -> "Helvetica", FontSize -> 14}} to specify the default font ...
11
votes
4answers
746 views

Why do some CountryData flags render at low resolution?

This question is related to data analysis introduced here Why do some flag images from the CountryData dataset render at very low resolution both in Front End and ...
10
votes
1answer
1k views

How does Mma compute Confidence Intervals?

I am trying to understand how Mma computes the Confidence Intervals after a NonlinearModelFit. Consider the following example: ...
10
votes
7answers
1k views

How do I get rid of a “jump” in my plot?

How can I prevent plotting functions from "connecting" inside a plot points that should "wrap around" outside the plot? For example, how do I eliminate the horizontal lines running across the ...
9
votes
6answers
2k views

How to simplify a complicated Sum in terms of power Sums?

For example, I have: $a=\sum _{r=1}^n x_r \left(\left(\sum _{i=1}^n x_i-x_r\right){}^2-\sum _{i=1}^n x_i^2\right)$ ...
9
votes
3answers
5k views

Is there a simple way to plot complex numbers satisfying a given criteria

I think this should be straightforward, but I cannot seem to find a good source on how to do it after searching around, so I'm trying to sketch sets of complex numbers that meet a given for criteria. ...

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