Routine delta2xi

From matrix form to vector form.

Description

This routine converts a block-diagonal operator Δ from matrix form to vector form.

Syntax

xi=delta2xi(delta,blk)

Input arguments

 deltaMatrix form of Δ=diag(Δ1,...,ΔN).
 blk

Matrix defining the structure of Δ. Its first 2 columns must be defined as follows for all i=1,...,N:

  • blk(i,1:2)=[-ni 0] → Δi = δiIni with Δi real,
  • blk(i,1:2)=[ni 0] → Δi = δiIni with Δi complex,
  • blk(i,1:2)=[ni mi] → Δi $ is a full ni x mi complex block.

Output argument

 xiVector form of Δ.

Example

blk=[-3 0;2 0;2 3];
xi1=(1:15)';
delta=xi2delta(xi1,blk)
xi2=delta2xi(delta,blk)

See also

xi2delta