Matrix

Gnuplot can interpret matrix data input in two different ways.

The first of these assumes a uniform grid of x and y coordinates and assigns each value in the input matrix to one element M[i,j] of this uniform grid. The assigned x coordinates are the integers [0:NCOLS-1]. The assigned y coordinates are the integers [0:NROWS-1]. This is the default for text data input, but not for binary input. See matrix uniform (p. ) for examples and additional keywords.

The second interpretation assumes a non-uniform grid with explicit x and y coordinates. The first row of input data contains the y coordinates; the first column of input data contains the x coordinates. For binary input data, the first element of the first row must contain the number of columns. This is the default for binary matrix input, but requires an additional keyword nonuniform for text input data. See matrix nonuniform (p. ) for examples.