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### Loops and subroutines [duplicate]

Possible Duplicate: Alternatives to procedural loops and iterating over lists in Mathematica I am new to Mathematica and not familiar with functional programming. In particular, I have no idea on ...
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### Seeking faster method than using Table and If together [duplicate]

See the example below. Is there any way to make this execute much faster and still get the same output ? I have read Conditionals slower than operators? but it didn't really help me as I can't seem to ...
572 views

### For loops in Mathematica [duplicate]

I'm actually the first time using loops in Mathematica. For example, I have: For[i = 1, i <= n, i++, For[j = 1, j <= n, j++, ....] How it is possible now ...
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### How should I go about writing more functional and list based code? [duplicate]

I've heard that Mathematica is usually faster when the code is list-based and/or uses a functional paradigm. I'm still working on getting the hang of this; there are a lot of ...
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### What are some general strategies to avoid using For loops? [duplicate]

Possible Duplicate: Iterating over lists in Mathematica While there are some cases where a For loop might be reasonable, it's a general mantra – one I ...
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### Want explanation of when different looping constructs are appropriate [duplicate]

For example when would you use a Do loop over a For loop? For which tasks would you use Map, ...
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### What techniques have you employed to avoid loop in Mathematica? [duplicate]

It appears to me that loop in mathematica is very slow (compared with matlab). Since many people still use mathematica to finish their work, there must be some techniques to bypass this problem. ...
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### What are the most common pitfalls awaiting new users?

As you may already know, Mathematica is a wonderful piece of software. However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ...
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### Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
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### Map a function across a list conditionally

It seems that this is a really basic question, and I feel that the answer should be obvious to me. However, I am not seeing. Can you please help me? Thanks. Suppose I have a list of data ...
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### Why should I avoid the For loop in Mathematica?

Some people advise against the use of For loops in Mathematica. Why? Should I heed this advice? What is wrong with For? What ...
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### Are there any cases when For[] loops are reasonable?

To my mind the only reason for the existence of For[] loops in Mathematica is to allow new users with some experience in procedural programming languages to write ...
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### How do I check if any element in a list is positive?

As a simple example of what I would like to do, suppose I have a list a of all real numbers. I would like to perform a simple check to see if some element of ...
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### Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
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### Finding the midpoints of an ordered list of numbers

Suppose that I have an ordered list of numbers. The numbers in the list may be evenly spaced, but they may not be. Here are two examples, list1 and ...
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### Removing all values from a list that satisfy a given condition

Suppose I have a list, list = Table[{n}, {n, 1, 5}] (* list = {{1},{2},{3},{4},{5}} *) and I want to remove all values from this list that are greater than 3, so ...
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### Shorthand for map at level 2

I love the shorthand /@. It is amazing for readability (and laziness when typing). However, right now I find that I need Map at level 2, i.e. ...
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### Creating custom functions with multiple arguments

I am hoping that this isn't a stupid question so feel free to vote it for closure. Google failed somehow. I want to define a custom function (more complicated than the usual ...
Picard's Iteration is a way of solving the IVP $$y'(x)=f(x,y(x)), \quad y(x_0)=y_0$$ It consists of defining the following sequence of functions recursively: $$y_0(x):=y_0 \\ y_{n}(x):=y_0+\int_{... 6answers 3k views ### Selecting elements from a list one by one I have an list: l = {{4,5},{7,8},{9,5},{3,2},{1,2},{13,12}}. I want to take the elements in the list in the sequential order. For example the first element in ... 4answers 495 views ### The gap between MapAt and ReplacePart for 2D data tables with headers Consider a relational table derived from survey data, where each column ("001-01" ...) represents a responder and each row (... 5answers 906 views ### What is primary, function computation or function application? What is the order of computations here? g[x_]:=x^2; f[x_]:=Sqrt[g[x]]; Map[f, Range[100]] Does this code first gets f(x)=x and then gives its values or for ... 5answers 1k views ### Relational joining of tables A common thing to want to do with data is to combine it (at least I thought this was a common thing). In SQL there is the idea of table joins "select id,v1,v2 from A,B where A.id=B.id" kind of thing. ... 3answers 303 views ### First evaluation fails I am fairly new to Mathematica (version 7), so please bear with me... I have duplicated, in Mathematica, a program that I originally wrote in C (it generates OEIS sequence A191837). The problem is ... 3answers 6k views ### Loop through a list and select elements I am new to Mathematica and I have no idea how to make a basic for loop work. I want to loop through the elements of a list: Range[45, 200]. I want to select the ... 3answers 689 views ### Rewriting For loop to FoldList or similar In CrossValidated, the answer to a question on prediction of number of viewers of Gangnam Style is given in R. I have mapped the answer directly to Mathematica: ... 3answers 860 views ### Is Table the only functional way to construct nested loops in Mathematica? Suppose you have a cubic box containing identical particles and you want to compute the distances between each particle and every other particle in the box without double-counting (i.e., if you've ... 3answers 1k views ### In nested For-loops, I want the second For-loop to be evaluated only once in each cyle I want to print A[0, 0, 1], A[0, 0, 2], A[1, 1, 1], A[1, 1, 2], A[2, 2, 1], A[2, 2, 2] using the following code. ... 4answers 4k views ### How to export data from For loop in text file? I'm new in Mathematica and I am trying to write numbers from 1 to 10 in txt file. But "Null" is everything that is written in my file. The code is: ... 3answers 1k views ### How to speed up a process I am wondering how to speed up the following code: Currently it takes more than two sec to be processed. ... 3answers 4k views ### How do I show the combined plot from the do-loop? I have a do-loop to do the calculations from a set of data and plot the graphs with different results, that was obtained from the calculations. I was able to get multiple graphs but I want to ListPlot ... 1answer 3k views ### converting Matlab program to Mathematica code I have the following Matlab program; ... 4answers 4k views ### Finding the area of a circle using monte carlo simulation [duplicate] I wrote the following code to find the area of the circle x^2+y^2=1 using monte carlo simulation : ... 3answers 1k 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 <... 5answers 2k views ### Assigning a particular value to array elements I have an array of 10000 elements. I want to randomly assign energy to these 10000 elements using Gaussian or Exponential distribution, such that each time a particular element is selected its energy ... 3answers 480 views ### What is the right way to write a function that includes other functions? I want to include multiple sub functions: b(x) = 10x w(x) = s + b(x) c(x) = x^2 into two main functions: ua(x) = w(x)-c(x) ub(x) = w(x)-c(x)^2 As a reaction to this answer, I wrote ... 4answers 255 views ### How to avoid writing K loops? I want to evaluate a mathematical function of K variables each of variables varying between 1:N. One way to do this is writing K loops and varying variables accordingly, as shown below: ... 2answers 165 views ### Achieve performance that is competitive with numpy [duplicate] What are the best practices to ameliorate time performance of Mathematica? As a practical example how we can decrease timing below? ... 2answers 479 views ### CUDA image processing I am having an issue with image processing involving CUDALink. ... 3answers 2k views ### Draw grid lines at multiples of k Here is a beginner's question: when creating plots with mathematica, I want the grid lines to be at multiples of a constant value. E.g. in the following plot, the vertical grid lines are at multiple ... 3answers 393 views ### Alternative forms to Table for iterating over replacement rules I have a multivariate polynomial x. I get coefficients of various monomials using CoefficientRules, which returns a list of ... 1answer 7k views ### How do I store values in a for loop into an array and then plot that array? [duplicate] What my title said and I want to plot the values of the array. still new to mathematica and programming so its hard to formulate my question just right 1answer 907 views ### 3 hour calculation? ParallelMap & ParallelTable I'm having some problems with slow Mathematica code... I'm basically doing a computation that's is expected to take 3 hours (!) in my Core i7 with 4 processors... I'm basically computing an index (of ... 3answers 1k views ### Stop Computation - Is Exit[] overkill? The following example either finds a factor of the number n or returns a message saying that the number in question is prime (I specifially wrote this to demonstrate my question below). ... 2answers 395 views ### Can't use my own discontinuous coefficient within NDSolve I want to evaluate the pendulum's motion with changing equilibrium state given by eqilValue[t]: ... 2answers 227 views ### Confusing ReplaceRepeated & Hold I've been bootstrapping myself to the very alien world of Mathematica and there came my first WTF moment: ... 3answers 451 views ### How to populate a large sparse array efficiently I am trying to populate a large 2D sparse array and sum up all the columns at the end. I tried generating a set of rules and then generate a matrix using SparseArray or break the data into chunks but ... 3answers 271 views ### Declaring lists Do I have to declare a list before using it in a loop? for example: For[i = 1, i < 10, i++, A[[i]] = i]; The output is: ... 3answers 325 views ### Question about Map and Total Suppose I have a list and I want to generate a new list, such that$$ NewList[index] = \sum_{index \neq j}^{NumOfElts} \frac {1}{ \lvert OldList[index]-OldList[j] \rvert ^2 }  Can I do it using ...
I want to have a simple script that gives me all numbers $k \in \mathbb{N}$ in some range such that product of all their divisors is equal to $k^3$. Here is the code that I wrote: ...