17k 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 Mathematica?...
4k views

### What best practices or performance considerations are there for choosing between Cases, Position, Pick and Select?

Cases, Select,Pick and Position each have different ...
• 34.3k
6k views

### How to splice together several instances of InterpolatingFunction?

I have a set of InterpolatingFunction returned by NDSolve which are valid over different (but overall continuous) domains. How ...
• 775
1k views

### How to find all the positions of max value of a list efficiently?

For Example, list=RandomInteger[{1,100},2000]. Yes,I know Position[list,Max[list]] can do. But it's based on pattern matching!...
• 1,854
3k views

### Find longest sequence of zeros in list

How it is possible to find the length of the longest sequence of zeros in list {1,0,0,1,1,0,0,0,0,1,0,0,0,1,1,0,0,1} which is equal to 4 in the sample list above
• 3,491
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### Incompatible Changes since Mathematica Version 7?

There is documentation of the incompatible changes made to Mathematica with each major release: Incompatible Changes since Mathematica Version 1 Unfortunately that documentation simply stopped ...
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825 views

### Generating Linear Extensions of a Partial Order

Given a set $S$ and a partial order $\prec$ over $S$, I'm looking for a way to "efficiently" generate a list of linear extensions of $\prec$. Suppose the partial order is given by a ...
• 445
1k views

### How to interpret the FullForm of a SparseArray?

SparseArrays are atomic objects, but they do have a FullForm which reveals information about them. What is the meaning of the ...
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1k views

### What are some useful (or hidden) properties of MeshRegion?

There is quite a bit of powerful functionality built in to MeshRegion, but it seems to be lacking in some areas. For example: extracting a list of edges that live ...
• 758
1k views

### SparseArray row operations

Given a large (very) sparse matrix, A, how can I efficiently "operate" on only the nonzeros in a given row? For example: For each row in A, generate a list of column indices that have a magnitude (...
• 758
3k views

### Get positions of all non zero matrix elements

I want to find all non zero elements of a table and I want to create a list that contains the name of the table the element was removed from, the position of the element, and the value of the element. ...
• 2,254
217 views

### Support for low-complexity (compressible) lists

By "low-complexity list" I mean a list like the following: lcl = {17, 17, 17, 17, 17, 21, 21, 21, 21, 21, 21, 21, 21, 11, 11, 11, 11, 11, 11, 11} ...
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465 views

### directly change the background value of a SparseArray?

given a SparseArray s = SparseArray[{1, 10} -> 1, {1, 10}, a] I can extract the background value (see What are SparseArray ...
• 39k
927 views

### Replace non-zero elements with symbol

I have a very large matrix (tensor) in Mathematica with some zero and non-zero elements. I am interested in replacing the non-zero elements with some symbol or a 1 so that it is easier to view the ...