39
votes
8answers
7k views

How do you convert a string containing a number in C scientific notation to a Mathematica number?

Suppose I have a string containing the C-representation of a floating point number, for example s = "1.23e-5" and I want to convert this to a Mathematica number. ...
20
votes
2answers
4k views

How to fit 3 data sets to a model of 4 differential equations?

I'm a biologist and a newbie in Mathematica. I want to fit three data sets to a model consisting of four differential equations and 10 parameters. I want to find the parameters best fitting to my ...
119
votes
6answers
4k views

How can one find undocumented options or option values in Mathematica?

Mathematica has a lot of undocumented or poorly documented options. How does one go about working out if there is an undocumented option that might solve a particular problem? How does one work out ...
37
votes
5answers
18k views

How do I clear all user defined symbols?

Is there some way to do this other than going to Evaluation -> Quit kernel and firing a new one up?
17
votes
4answers
1k views

Elegant manipulation of the variables list

I have a list of global variables (some of them are indexed variables), for example: varsH = Hold[U0[1], U0[2], B0, V0[1], V0[2]] Or (if it is easier to handle) ...
67
votes
2answers
13k views

Mathematica 10.0.x freezes in Initializing kernels

Bug caused by paclet update and fixed by paclet update. I updated to Windows 10 and have been running Mathematica fine on it for over a month. For some reason, it has just stopped working. I don't ...
21
votes
5answers
1k views

How to perform a depth-first preorder traversal of an expression?

Due to confusion of terminology on my part I asked the wrong question before. Since it has already received other answers I shall not edit it, but instead ask the question I meant to in the first ...
11
votes
3answers
6k views

General::ivar is not a valid variable when plotting - what actually causes this and how to avoid it?

I was just evaluating a couple of expressions and started to get errors like this: ...
106
votes
12answers
5k views

What are some useful, undocumented Mathematica functions?

There have already been some questions about some undocumented functionality in Mathematica. Such as (please add to these lists!) How can one find undocumented options or option values in ...
28
votes
2answers
9k views

Can we use letter with a subscript as a variable in Mathematica?

I tried Subscript[a, 0] = 1 (* 1 *) Clear[Subscript[a, 0]] ...
18
votes
4answers
11k views

Finding unit tangent, normal, and binormal vectors for a given r(t)

For my Calc III class, I need to find $T(t), N(t)$, and $B(t)$ for $t=1, 2$, and $-1$, given $r(t)=\{t,t^2,t^3\}$. I've got Mathematica, but I've never used it before and I'm not sure how to coerce ...
15
votes
5answers
1k views

How are parameters evaluated for a Plot in Manipulate

I am trying to get my head around how Manipulate evaluates functions in a Plot. I have read the introduction to Manipulate, and introduction to Dynamic, but I still ...
18
votes
6answers
2k views

Annoying display truncation of numerical results

I have a lot of data to inspect. An example of a number in my program is 123.189094 This gets displayed as 123.189 ...
93
votes
2answers
8k views

How to manipulate 2D plots?

When it comes to visual analysis, large datasets or data with intricate internal details often makes plotting in 2D useless, as the outcome is either just a fraction of the full dataset, or no details ...
53
votes
5answers
13k views

How to find all the local minima/maxima in a range

I want to find : all local maxima in range all local minima in range From those points I can interpolate and combine functions upper and lower boundary. What I am really interested in, is the ...
28
votes
6answers
2k views

Mathematica Destructuring

Context I'm writing a function that look something like: ...
38
votes
4answers
3k views

Can I simplify an expression into form which uses my own definitions?

This seems like a simple thing to do, but I couldn't find anything relevant from Mathematica documentation. So suppose I have an expression: a*b/(a + a*Cos[a/b]) ...
28
votes
5answers
4k views

Clear complains that a subscripted variable is not a symbol or a string?

Here's a small listing where I've used EscqEsc to typeset θ in the notebook: ...
8
votes
3answers
4k views

Assigning values to a list of variable names

As part of a calculation I need to do something like this Evaluate[{aaa, bbb, ccc}[[ index]]] = {1, 2, 3, 4, 5} so if index is ...
13
votes
1answer
2k views

What is the difference between Set and SetDelayed?

I have a problem with defining a function and most of time I get confused by Set or = and ...
49
votes
3answers
6k views

Understanding CDF

Update Since more and more issues are revealed as I venture deeper into the world of CDF, I decided to make this thread more general and hopefully more useful. I know posted my findings as an answer, ...
42
votes
2answers
2k views

when is f@g not the same as f[g]?

I have always thought that f@g will give the same result as f[g] in all cases, and it is just a matter of style which one to use ...
31
votes
4answers
1k views

Can a function be made to accept a variable amount of inputs?

I have a function that takes two inputs and processes them for a single output. What I need is one that can take a varying number of inputs. and process them to a single output. Is this possible in ...
26
votes
2answers
2k views

Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
16
votes
4answers
3k views

How to modify function argument?

Usually in programming languages, function arguments are normal local variables, which can be modified. Is this not true in Mathematica? ...
84
votes
6answers
16k views

$\LaTeX$ and Mathematica

I quite often would like to draw graphics in my $\LaTeX$ documents using Mathematica. I have encountered three problems. I would like to know if there are any workarounds to these problems I would ...
91
votes
1answer
3k views

Programmatic formatting for Mathematica code - possible?

It seems to be both an interesting programming challenge and a very useful practical application to have a Mathematica program which would allow one to pretty-print Mathematica code, so that it is ...
75
votes
3answers
7k views

Recovering data points from an image

Unfortunately, some data can only be obtained in picture form (Japanese publications anyone?). Since this cannot be worked with, it has to be converted to a dataset that can; I was wondering whether ...
78
votes
8answers
3k views

Functional style using lazy lists?

Let's say I want to answer the question "what are the first 400 palindromic prime numbers?" The first approach that comes to my mind from the set of languages that I know is to use some sort of lazy ...
46
votes
3answers
6k views

Placing a ContourPlot under a Plot3D

I would like to combine a 3-dimensional graph of a function with its 2-dimensional contour-plot underneath it in a professional way. But I have no idea how to start. I have a three of these I would ...
52
votes
2answers
3k views

Internal`Bag inside Compile

Since Internal`Bag, Internal`StuffBag and Internal`BagPart can be compiled down, it is a ...
23
votes
4answers
2k views

how to differentiate formally?

I have been wrapping my head around this for a while now and I have not found a solution so far. I want to work with an arbitrary number of variables in mathematica and use some built in functions. ...
18
votes
3answers
544 views

How can I get the unchanged Box form of an arbitrary expression?

One may observe that MakeBoxes does not give the actual Box form of various expressions: MakeBoxes[{1*^4, 000123, a*b c}] ...
19
votes
2answers
1k views

Using a list of tuples in a pure function

I want to use a list of tuples within a function to make assignments. Say I want to make assignments of the form value[i,j] = val What I have is a list of ...
70
votes
2answers
3k views

Flatten command: matrix as second argument

One thing I could never wrap my head around is how Flatten works when provided with a matrix as the second argument, and the Mathematica help isn't particularly ...
71
votes
1answer
3k views

Open-source IntelliJ IDEA plugin to support Mathematica development

Although we already had a question asking for development alternatives to Wolfram Workbench, I want to ask a more specific question: One of the most advanced IDE's especially for Java programming ...
57
votes
7answers
2k views

Functions vs. patterns

Every time I define a new function, I wonder which construct I should use: true functions obtained by using Function, or rule-based syntax. For example, these are ...
50
votes
2answers
2k views

Is there a way to separate variables between multiple notebooks?

I often correct homework by checking the calculations in Mathematica. Sometimes you would like to have two solutions open at once. However often defined symbols such as ...
47
votes
7answers
2k views

How to “Copy as Unicode” from a Notebook?

I spent some time manually editing a post replacing Mathematica ASCII \[Alpha] with Unicode α. I did this by laboriously ...
33
votes
3answers
7k views

ListPlot with each point a different color and a legend bar

I would like to generate a ListPlot with the color for each point in the plot corresponding to a particular value (not associated with the position in the plot). I'd then like to add a legend ...
28
votes
3answers
7k views

ShowLegend values

How do I get ShowLegend to put the max and min values that a plot produces. for example, when using ListDensityPlot, with ...
38
votes
2answers
4k views

Generating a broken or snipped axis in ListPlot

I have two data sets, data1 and data2. For example: ...
48
votes
2answers
1k views

Head and everything except Head?

I have been working on picking expressions apart using Head and Part and encountered a little mystery. Consider the canonical ...
18
votes
3answers
1k views

How to get the real PlotRange using AbsoluteOptions?

The problem in general involves the unreliable behaviour of AbsoluteOptions when option values are implicitly specified (e.g. ...
48
votes
2answers
4k views

What is so special about Prime?

When we try to evaluate Prime on big numbers (e.g. 10^13) we encounter the following issue: ...
25
votes
1answer
514 views

Why doesn't PatternTest work with Composition?

While playing around with the solutions to this question, I've found some very strange behaviour: ...
80
votes
6answers
6k views

Minimal effort method for integrating C++ functions into Mathematica

As of Mathematica 8, what is the minimal effort way to integrate an existing C++ function into Mathematica? I think we have these: MathLink (it was quite long ago I used it last time) communication ...
49
votes
5answers
1k views

How to avoid nested With[]?

With[ {v1 = #}, With[ {v2 = f[v1]}, g[v1, v2] ] ] How to avoid nested With[] like the above? I'd like to use ...
45
votes
4answers
2k views

How can I implement dynamic programming for a function with more than one argument?

Dynamic programming is a technique for avoiding the repeated computation of the same values in a recursive program. Each value computed is immediately stored. If the value is needed again, it is ...
42
votes
7answers
2k views

Character edge finding

The following line of code finds the edge of a character: ...

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