How to duplicate a 2D matrix to build a 3D matrix

This Help Article explains how to build a 3D matrix by duplicating a 2D matrix, without using a loop in IDL.

An example 2D matrix (to be duplicated into a 3D matrix) is shown below:

b=[[1,2],[3,4]]

print,b

       1       2

       3       4

 

The following steps can be used to replicate this matrix 3 times in a 3D matrix:

Step 1: reform the 2D  matrix B as a 1D vector

b=REFORM(b,4,1)

print,b

      1       2       3      4

 

Step 2: create a 2D matrix by replicating 3 times the previous vector

b=b#REFORM(intarr(3)+1,1,3)

print,b

          1          2           3           4

          1          2           3           4

          1          2           3           4

 

Step 3: reform the 2D matrix B as a 3D matrix

b=reform(b,2,2,3)

help,b

B               LONG      = Array[2, 2, 3]

print,b

           1           2

           3           4

 

           1           2

           3           4

 

           1           2

           3           4