Two-dimensional waves in Igor Pro

A matrix is a wave with two dimensions, and MatrixOP is the fast way through one.

Function/WAVE ColumnMeans(WAVE m)
    Variable rows = DimSize(m, 0), cols = DimSize(m, 1)

    Make/O/N=(cols)/D means
    MatrixOP/O means = sumCols(m) / rows

    Make/O/N=(rows, cols)/D centered
    centered = m[p][q] - means[q]

    Printf "%d by %d, centered\r", rows, cols
    return means
End

How it works

1. w[i][j] indexes rows and columns; p and q do it in an assignment.
2. MatrixOP runs a whole expression in one pass, in C.
3. DimSize(w, 0) is the row count, DimSize(w, 1) the columns.

Keywords and builtins used here

• DimSize
• End
• Function
• Make
• MatrixOP
• Printf
• Variable
• WAVE
• return

The run, in numbers

Lines

12

Characters to type

271

Tokens

78

Three-star pace

85 tpm

At the three-star pace of 85 tokens a minute, this run takes about 55 seconds.

Type this snippet

Step 4 of 4 in Signals & matrices, step 14 of 16 in Waves & analysis.

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