How do I write a sparse matrix in MATLAB

[Daniel Pollard]

This should help.

[Shlesha Van]

That gives solutions on how to convert a full matrix into sparse. My case is opposite. I want to convert a sparse into full

Answer 1

[Daniel Pollard]

https://uk.mathworks.com/help/matlab/ref/full.html

[Shlesha Van]

Thanks Daniel, but how do I type this matrix in Matlab?

I tried A = [ 2 -1 0 ... 0;]; but everything after ... turns green.

[Daniel Pollard]

An ellipsis ... has a very specific meaning in Matlab. If you type it in, it interprets that to mean "the next line is a continuation of this line". It does not mean "fill in the numbers here". A sparse matrix is a specific thing, and if you try to enter exactly the A in your question into Matlab, you'll have a bad time. I recommend reading the documentation to get a clearer idea of what's going on.

[Shlesha Van]

[Jan]

The first two inputs of sparse() are the size of the matrix. As the error message tells you, [2,-1,0] cannot be a valid size. See the documentation of sparse :

doc sparse

Answer 2

[Jan]

You want to convert a sparse matrix into a full one? Then use the command: full().