Questions about the use of built-in Mathematica functions, including pure functions.

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1
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0answers
56 views

How to apply an rule to factors matching a certain form

Suppose we have many expressions involving irrational ArcTan expressions (such as ArcTan[Sqrt[3],5]) along with other irrational factors (such as ...
1
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1answer
138 views

Time Varying Payoffs?

I'm trying to write some code that will return the final value of an annuity whose monthly payouts may or may not be constant each month. Right now I have working code for constant payments, but I'm ...
4
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1answer
112 views

How to apply RootLocusPlot correctly

I have to analyze the complex regions of variable c which is define obtained with InverseLaplace help in the form ...
0
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1answer
136 views

How to define a function that operate with a base case recursively? [duplicate]

Let's start from the simplest case: say I have a function $f(x)=x$, and let's say I want to define a new function (of $x$) to be its $n$-th power $(f(x))^n$. How should I write the code? I tried: <...
3
votes
2answers
792 views

Differential operator squared

I defined a one-dimensional momentum operator $\hat{p}=-i\hbar\frac{\partial}{\partial{x}}$ in Mathematica p = -I * h * D[#, x]& and I want to get the ...
2
votes
0answers
112 views

Are there some other ways to solve a second PDE except DSolve?

I have a partial differential equation as follows: $$\frac{\partial p(x,t)}{\partial t}=\text{Dp} \frac{\partial ^2p(x,t)}{\partial x^2}-\frac{p(x,t)-\text{p0}}{\tau }$$ What I try to do was to get ...
0
votes
3answers
443 views

How to combine multiple functions into a single function, indexed bya new argument

I have a system of expressions (matrices) which correspond to increasing orders of precision in a theory. These expressions are quite complex (require about 40+ lines of code to produce) and are not ...
3
votes
1answer
172 views

Arguments for ChartElementFunction

I was reading the documentation for BubbleChart and I saw this example ...
3
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0answers
517 views

Slow mixture fitting when having ill-conditioned covariance matrices. How to make it faster?

I'm using Mathematica 9.0 to fit multidimensional observations with a gaussian mixture. To do so I first adapted these steps to ensure that the mixture parameters are well defined (see http://...
1
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2answers
858 views

Using Array Elements as Function Arguments

Suppose I have an array p = {a,b,c,d} and a function f that takes a variable number of arguments. I want to evaluate ...
2
votes
1answer
154 views

Can I make a function which depends on several arguments which are not independent?

Here's a simple example Suppose have the permanent relation that z is proportional to xy^2, for real numbers s. z = s x y^2 Now, we are interested in ...
0
votes
0answers
31 views

Problem with slot in If statement [duplicate]

I am struggling with slots, In this case I have a function int which gives either true or false. When it gives true, I want ...
11
votes
1answer
286 views

Why does Plot[Hold[x], {x,0,1}] work?

It appears that, counter to my expectation, all of these (and probably many others) seem to work fine: ...
2
votes
0answers
115 views

How is Wolfram Language different than regular Mathematica? [duplicate]

From all I can see there seems to be no difference between "Wolfram Language" and regular Mathematica. Is Wolfram just a marketing rebranding of Mathematica or is there a new capability I am missing?
13
votes
4answers
663 views

How to make a function with its own options as well as passing options to other functions [duplicate]

I have a function with many of its own options, but I would also like to pass options to subfunctions using the FilterRules function. Here's a simple example: <...
3
votes
1answer
326 views

Fixed-Point Numbers in Mathematica

I am working with a library that needs input in a Fixed Point notation. I’d like to figure out a way to convert the floating point results into fixed point representation. The fixed point length is ...
0
votes
1answer
78 views

How to use ImageMultiply[] over a list of strings?

I'm trying to do the following: ...
6
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4answers
326 views

Using an ellipse as a threshold for Nearest function

The Nearest function can receive as a threshold parameter a radius to look for elements inside that. From the documentation: ...
3
votes
1answer
102 views

Why is left NumberPadding always applied in NumberForm?

I would like to display numbers like 9.0001 and 10.0001 in the fixed-width form of xx.xxxx. ...
0
votes
1answer
3k views

Finding equation of tangent line at a point [duplicate]

my function is defined as f[x_] = x^1.1 - 2.5 x^.5 I need to find the equation of the tangent line to the curve using the point slope form which would be something like f'[a][x+a]+f[a] a=1 and x=1 ...
0
votes
0answers
22 views

Question about a ParametricPlot with a shading grey family of lines and/or different sizes [duplicate]

So, I have this function of the polar angle $\theta$, with a varying parameter $t$: {Cos[\[Theta]] (1 + Sin[t]), Sin[\[Theta]]} and I want to draw it in a ...
5
votes
1answer
158 views

Can Mathematica Operators be combined in a linear fashion for readability? [duplicate]

Here's a simple example. Suppose we want to find the off-diagonal matrix of m: m={{1,2},{3,4}} This can be solved fairly simply by extracting a list of the ...
7
votes
2answers
634 views

Define a function with a function for an input

I want to create the functions $even[f]$ and $odd[f]$ which will apply the formula $even[f(x)] = \frac{f(x)+f(-x)}{2}$ and $odd[f(x)]=\frac{f(x)-f(-x)}{2}$ for an arbitrary $f$. I tried using <...
5
votes
2answers
1k views

Quickly calculating the mean / median of a function over an interval

I'd like to calculate the Mean or Median value of a function over some interval $[a,b]$. However, I can't seem to find how to do this in help. Specifically I'd like to have something that works like ...
1
vote
1answer
123 views

How can I check if one expression implies another?

Say I have one expression, for example $x^3-3 + c = y$, and I want to check if it implies another with some set of explicitly stated assumptions. With the previous example, assuming all variables are ...
1
vote
2answers
825 views

Multiple curves plotted with different colours [duplicate]

I am trying to use ColorFunction for 2 functions on the same plot. I only want the cubic equation to change colour. ...
2
votes
2answers
133 views

Testing for arbitrary algebraic expression in given variable

I want to test, for example with MatchQ, if the argument of a function is an arbitrary expression in a single or several variables whose names can be assumed to be ...
0
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0answers
46 views

Using Table[ ] vs using Do[Append [ ] ] [duplicate]

Is it generally better/faster to use the Table function over using Do[Append []]? For example, I have this piece of code: <...
0
votes
1answer
638 views

Pass unevaluated function with evaluated arguments

I am almost sure that this question has been asked somewhere. I found similar ones, but I cannot find exactly what I need, which might mean that I am on the wrong track. I search a method to pass an ...
8
votes
2answers
290 views

Make Sinc'[0] return 0 instead of Indeterminate

I want Sinc'[0] to return 0, but instead it returns Indeterminate. I've tried Unprotect[Sinc] Unprotect[Derivative] Derivative[1][Sinc][0] ^= 0 But it doesn't ...
0
votes
1answer
80 views

How to write series of Do[ ]'s with a single Table[ ]?

Edited to provide more information (sorry I don't know how to format matrices here) I would like to replace: m = 4; ...
0
votes
0answers
52 views

Generating Suffixes [duplicate]

I am doing a large Matrix calculation in which I need to generate symbols first like $F^{\mu\nu}$ I would like to get $\mu\nu = 00, 11, 22, 33$ and so on. I need to have the symbols before I can ...
0
votes
2answers
179 views

How can I improve Do loop?

I have very large input of time series data (over 30000 observations) that look like as follows: ...
7
votes
2answers
257 views

Evaluation in lambda function

If I have a function, that returns a function, for example: f[a_] := a^2 * # & then f[3] == 3^2 # & Is there a way ...
1
vote
1answer
220 views

How to define a summation with function calling itself?

I am new to Mathematica. I want to do this f(x)=summation f(t), summation is over t, where 1<=t<=x-1 and mod(x+1,t+1)=1, i.e. when x+1 is divided by t+1, remainder is 1 and f(1)=1. Should i use ...
0
votes
1answer
146 views

Integration of DiracDelta

I just came across the following curiosity and I'm not sure whether it's a bug or just me missing something. Here's a minimal example: I defined the following "function" ...
2
votes
3answers
151 views

Creating a function as a table of derivations

Suppose I have function, which is in fact a list of $n$ functions with $n$ parameters f = {#1 + #2^2 + #3^3, #1^2 + #2^3 + #3^4, #1^3 + #2^4 + #3^5}& I want ...
0
votes
2answers
143 views

How to display output as symbols?

I have this piece of code which populates a matrix following different rules depending on row and column number: ...
3
votes
3answers
590 views

For-loop not working as I expect

I want to do this: When 10 <= t < 130, give t -> 1; When 130 <= t<300, give ...
5
votes
3answers
2k views

cross-correlation with time lag

I have two lists with some data. a={1,2,3,4,5} b={5,4,3,2,1} Now I want to compute the cross correlation of the two lists with a time lag of 1, like it is ...
0
votes
2answers
160 views

Handling output that was returned unevaluated from a function

When evaluating functions, including those described in this post, how do Mathematica users handle values returned from a function that are unevaluated? For example (based on 1): ...
0
votes
2answers
290 views

Define a function on a parameter argument set to zero

Say I have an expression (matrix) that depends on several variables. f= {{a, b+c},{2a-b^2,c^5+a b}} I want to define new matrices with the single parameter ...
0
votes
4answers
346 views

Evaluate function from a table

I want to define list of functions and also use them for evaluation. But this just doesn't work. For example ...
0
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1answer
2k views

How to properly substitute values into variables?

I have an array of functions in terms of a[0] through a[n] and I wish to replace the a[]'s with previously calculated values p[0] through p[n], as in below: ...
2
votes
3answers
310 views

find connectivity

Imagine a chain of 20 rings, labeled by 1-20 sequentially. We want to make random size sets of numbers randomly chosen from these 1-20 rings. No duplicate numbers are allowed. Example of a set: $\{16,...
13
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0answers
322 views

How is the mysterious Raw function used?

I have never seen an example use for the mysterious Raw function: Raw[h, "hexstring"] constructs a raw data object with head h, and with contents ...
1
vote
1answer
293 views

Detecting a nonlinear edge in a 2D point pattern

Following an earlier post here, I have generated a point pattern on the unit square $[0,1]\otimes[0,1]$, which is described by a piecewise constant intensity function constructed so that (in ...
1
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0answers
72 views

Distinction between 2 NETTypeInfo answers

In a NETLink application I checked all the types offered by LoadedNETTypes[] according to the following: ...
0
votes
1answer
221 views

Extract information from function definition returned by DefineDLLFunction

I have an application using DefineDLLFunction whose output is: Function[Null, If[NETLinkDLLPrivatecheckArgCount["DRV_AOVoltageOut", {##1},2], ...
0
votes
2answers
364 views

How to find intervals in the domain corresponding to intervals in the range?

I want to find the intervals for the argument m1 of this function corresponding to the value for the function lying in given intervals of the range: ...