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### Which NDSolve method is most effective for the given chaotic system?

Note: This question is for those chaotic systems where the order of maximal Lyapunov exponent is around $10^{-3}$. So it's different from normal chaotic systems like Hénon–Heiles system, Yang-Mills-...
• 2,253
172 views

### Replacing the heads of an expression in left to right order

I would like to replace the occurrences of the head f in an expression. The expression only contains two possible heads: f and g. These heads are applied to exactly two arguments. Example: ...
• 1,688
81 views

### Undocumented behavior of Fold for arbitrary heads [closed]

Edit: I'm apparently blind. Sorry! And thanks to those who answered anyway. Apologies in advance if this is sort of a nitpicky question, but I'm generally very paranoid that I don't fully understand ...
• 111
179 views

### Why is Around omitted when the uncertainty is zero?

I have a list of values with errors and I use Around[x, dx]. Some of those values have an error of zero though. Mathematica removes the ...
• 53
304 views

### A problem on the pattern (:) of Heads

I defined Clear[f, g] f[(h : Exp | Log)[x_]] := x; g[(h : Log | Exp)[x_]] := x; The code gives a weird result: ...
• 193
475 views

### How can I create an atomic head or treat some head as atomic during Map?

For example, Map[g, {0, {h[1, 2, 3]}}, {-1}] gives {g[0], {h[g[1], g[2], g[3]]}} I want a ...
• 17.2k
59 views

### When should I use Audio vs Sound Data types?

It seems like mathematica has 2 related data types Audio and sound. Why is there 2 separate data types? When would I use one versus the other? Guesses I know I can convert between them by ...
• 981
43 views

### Can't match custom head in function signature [closed]

I have written a financial charting function which has the following signature; ...
82 views

### any way to store the values of the controls of a Manipulate so that one can reuse them in the future excutions

I’m using Manipulate[] to adjust several parameters, which will eventually generate some figures. After I get the desired view, I’d like to store the set of control parameters so that I can reuse them ...
• 735
254 views

### How many @ need to be used when I try to use apply function? [closed]

According to the manual, $f@@A$ means apply function $f$ to $A$. If it would be the same if I only use one @? Does $f@A$ still represent apply apply function $f$ to $A$? And it would help a lot if ...
• 107
126 views

### Extracting n-th part of an expression without any evaluation

Is it possible to extract n-th part of an expression as a string, without any evaluation? For example, ...
• 4,295
394 views

Can we say Head[x] and x[[0]] are identical ? In mathematica manual I could find : 'The head is the part with index 0' But I am not sure whether Head[x] are x[[0]] are really interchangeable in any ...
• 4,295
95 views

### Understanding f /@ g[x,y,z] [closed]

According to the Mathematica guide, In[26]:= f /@ g[x, y, z] Out[26]= g[f[x], f[y], f[z]] In a simple example, this works as desired with symbolic values: ...
• 143
1 vote
121 views

### How to use column header as the x-axis in ListPlot?

I imported a csv file, and the header of the columns are specific dates. How would I plot these points using ListPlot, but the x-axis instead of 1,2,3, etc, is the dates from the column headers? For ...
1 vote
100 views

### Dropping curly brackets from a list [closed]

I would like to make many plots using the same plot parameters. I am trying to define a plot parameter list such as ...
• 11
78 views

### Name of patterns cast as expressions from strings

I'm trying to match a part of a string while imposing conditions on the patterns, e.g.: StringCases["223", a: DigitCharacter ~~ b: DigitCharacter /; Unequal[a, b]] ...
• 483
75 views

### Count heads: e.g. neglect all terms $\sin(x) \sin (y) \sin (z) \sin (w)$ for all values of the argument

I have a polynomial (functional) expression $E[F]$ in terms of a function $F$. I want to take an $F$-cube truncation in the sense that I want to and make terms of the form $F[w]F[x]F[y]F[z]$ vanish ...
• 155
82 views

### Function matching any head (Example: h_[_,_] := 5)

I want to define a function matching any expression with 2 parameters. For example: _[_, _] := 5 I get the following error: SetDelayed::nosym: "[,_] does not ...
• 51
411 views

### How to remove style from a styled number?

For example, I have a number with style like so: Style[1, Red, 20] How do I remove its style, so it returns to its inner value 1...
• 599
810 views

I have a dynamic list of function names, like {f1, f2, f3, ...}, and they will enter in computation in various forms ...
• 543
1 vote
11 views

### Parsing the link returned by CloudExport

Consider Is there a way to make a function justLink that parses a CloudObject[<link>] and returns just the string ...
• 3,145
196 views

### Extracting terms with certain heads in a function

Given a function with several arguments func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3] I would like to extract all arguments with the head ...
• 601
218 views

### Why does MatchQ[a, r_ /; Head[r] != Plus] evaluate to False?

I'm trying to understand. Why is it that: MatchQ[a, r_ /; Head[r] != Plus] Evaluates to: False ? For me, I would think ...
• 1,447
3k views

### Why no RationalQ or RealQ?

Interesting pattern came up as I go through the homework replies of my students. Why is there no RationalQ or RealQ? We have <...
• 4,009
399 views

### Testing Head inside a Module [closed]

I hava a Module in which a want to give a single String or a List as a parameter and I want to change a single String to a List containing this String. So I did the ...
• 5,603
222 views

I was trying to find the order of highest derivative of expression. Using solution given in detect-highest-order-of-derivative-in-expression I just do not understand why when removing ...
• 145k
1 vote
1k views

Input Code a[1]=UnitVector[4,1] b[1]=1 Now I want replace the head of b[1] by a, ...
• 355
121 views

### How to obtain a list of all build-in system level Heads?

I am writing a small Mathematical expression parser and need a list of all Mathematica build-in Heads (system context?) so I can check the type of input. Such as ...
• 145k
235 views

### Replace Complex Head with List

I would like to apply ListPlot to a set of complex numbers. This is what comes to mind to convert a complex number to a pair: ...
• 183
128 views

### Gather element of a list based on their head

I have list of the form {y[-1], y[0], w'[1], y'[0], w'''[-1], z''[-1]} and I would like to gather the elements together based on their heads to have ...
• 525
673 views

### How can I replace a head on a specific level?

So in my notebook I have a list of long expressions which are sums of a bunch of terms. I would like to look at each of these terms individually and try to remove them based on some criteria. My idea ...
1k views

### How to "invert" a rule

The subject is a bit cryptic, I know, but here is what I'd like to do: Let's say I am solving an ODE like this: ...
• 4,149
356 views

### How to access Dataset's metadata

A Dataset object has internal metadata. For example, let ds = Dataset[{<|"a" -> 1, "b" -> "x", "c" -> {1}|>}]; ...
• 11.7k
86 views

### Why is head evaluation inconsistent in pattern replacement?

I noticed the following unexpected result: In[90]:= "foo" /. x_String -> Head[x] Out[90]= Symbol Why is it that Head[x] ...
• 377
337 views

### How to represent 1 as Symbol["Integer"]

Maybe this is a boring question, but I cannot figure it out. Because every expression has a Head, and Head[1] is ...
• 2,571
445 views

### How to Collect a variable multiplied by a constant?

I'd like to use Collect to get terms that have a variable multiplied by a constant. For example I'd like: Collect[x + b x, b x] ...
• 1,890
1k views

### What is the definition of head in Mathematica? [closed]

I know (by practice) what a head is, but I am unable to find the appropriate words to actually define it. I would like to see a precise definition of head using the appropriate technical words ...
1 vote
227 views

### Why does the Derivative function not appear in the tree form? [closed]

I was learning that set delay doesn't evaluate things until its calling time. Hence, I thought that something like the followng: dfdt := D[f[t],t] would not ...
707 views

### Is there any way to use head of Real and Integer altogether?

Is there any way to use the head of Integer and Real together like below? The below is not right, I know that, it is just for ...
383 views