Large scale linear algebra

What function would i use to figure out the memory a matrix uses?

Answer 1

[Matt J]

whos will work if you want the memory consumption of any variable including its metadata.

A=rand(10);

whos A

  Name       Size            Bytes  Class     Attributes

  A         10x10              800  double              

Note that this doesn't distinguish between deep and shallow copies. So, for example, in the code below, B is not really consuming an additional 800 bytes of memory on top of what A consumes (because it is just a shallow copy of A).

B=A;
whos A B

  Name       Size            Bytes  Class     Attributes

  A         10x10              800  double              
  B         10x10              800  double              

However, if you were to modify B in any way, Matlab would allocate B it's own 800 bytes.

[Eduardt Petrick]

thank you

[Matt J]

You're very welcome, but please Accept-click the answer if it resolved your question.

Answer 2

[Matt J]

When you store an MXN real double matrix in full form, you can expect that its matrix data will consume 8*M*N bytes. For a complex matrix, it will be 16*M*N, naturally. In either case, the calculation doesn't include the memory consumed by the variable's metadata.