Matrix

One of the types of objects in Praat. A Matrix object represents a function z (x, y) on the domain [xmin, xmax] × [ymin, ymax]. The domain has been sampled in the x and y directions with constant sampling intervals (dx and dy) along each direction. The samples are thus z [iy] [ix], ix = 1 ... nx, iy = 1 ... ny. The samples represent the function values z (x1 + (ix - 1) dx, y1 + (iy - 1) dy).

## Matrix commands

Creation:

  • Create Matrix...
  • Create simple Matrix...
  • Read from file...
  • Read Matrix from raw text file...
  • Read Matrix from LVS AP file...

Drawing:

  • Matrix: Draw rows...
  • Matrix: Draw contours...
  • Matrix: Paint contours...
  • Matrix: Paint cells...
  • Matrix: Scatter plot...
  • Matrix: Draw as squares...
  • Matrix: Draw value distribution...
  • Matrix: Paint surface...

Modification:

  • Matrix: Formula...
  • Matrix: Scale...

## Inside a Matrix object

With Inspect, you will see the following attributes.

xmin, xmax ≥ xmin
  x domain.
nx ≥ 1
  number of columns.
dx > 0.0
  distance between columns.
x1
  x value associated with first column.
ymin, ymax ≥ ymin
  y domain.
ny ≥ 1
  number of rows.
dy > 0.0
  distance between rows.
y1
  y value associated with first row.
z [1..ny] [1..nx]
  The sample values.

After creation of the Matrix, xmin, xmax, ymin, ymax, nx, ny, dx, dy, x1, and y1 do not usually change. The contents of z do.

Normally, you will want xmin ≤ x1 and xmax ≥ x1 + (nx - 1) dx.

## Example: simple matrix

If a simple matrix has x equal to column number and y equal to row number, it has the following attributes:

  xmin = 1; xmax = nx; dx = 1; x1 = 1;
  ymin = 1; ymax = ny; dy = 1; y1 = 1;

## Example: sampled signal

If the matrix represents a sampled signal of 1 second duration with a sampling frequency of 10 kHz, it has the following attributes:

  xmin = 0.0; xmax = 1.0; nx = 10000 ; dx = 1.0·10-4; x1 = 0.5·10-4;
  ymin = 1; ymax = 1; ny = 1; dy = 1; y1 = 1;

## Example: complex signal

If the matrix represents a complex spectrum derived with an FFT from the sound of example 2, it has the following attributes:

  xmin = 0.0; xmax = 5000.0; nx = 8193 ; dx = 5000.0 / 8192; x1 = 0.0;
  ny = 2 (real and imaginary part);
  ymin = 1 (first row, real part);
  ymax = 2 (second row, imaginary part);
  dy = 1; y1 = 1; (so that y is equal to row number)

### Links to this page

- ActivationList
- BarkFilter
- BarkSpectrogram
- CC: To Matrix
- Create simple Matrix from values...
- Eigen & Matrix: To Matrix (project columns)...
- Eigen & Matrix: To Matrix (project rows)...
- Eigen: Extract eigenvector...
- FormantFilter
- Formulas 1.6. Formulas for creation
- Formulas 8. Attributes of objects
- GaussianMixture & PCA: To Matrix (density)...
- LPC: To Matrix
- Matrix: Draw distribution...
- Matrix: Paint cells...
- Matrix: Set value...
- Matrix: Solve equation...
- Matrix: To TableOfReal
- MelSpectrogram
- PatternList
- Photo
- RealTier