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Computes a sparse or full identity matrix

Other toolboxes required none
Function category Helper functions
This is a helper function that only exists to aid other functions in QETLAB. If you are an end-user of QETLAB, you likely will never have a reason to use this function.

iden is a function that computes the identity matrix of the desired size, which is either full or sparse.


  • ID = iden(DIM,SP)

Argument descriptions

  • DIM: The number of rows (or equivalently, columns) that ID will have.
  • SP: A flag (either 1 or 0) indicating whether ID should or should not be sparse.


Full and sparse versions of the 2-by-2 identity matrix:

>> iden(2,0)

ans =

     1     0
     0     1

>> iden(2,1)

ans =

   (1,1)        1
   (2,2)        1


This function is only meant to simplify code within other functions. If you always want either the full or the sparse identity matrix, just use MATLAB's built-in eye or speye function.

Source code

Click here to view this function's source code on github.