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## Line Plots of Matrix Data

When you call the plot function with a single matrix argument

```plot(Y)
```

One line is plotted for each column of the matrix. The x-axis is labeled with the row index vector 1:m, where m is the number of rows in Y. For example,

```Z = peaks;
```

returns a 49-by-49 matrix obtained by evaluating a function of two variables. Plotting this matrix

```plot(Z)
```

produces a graph with 49 lines.

In general, if plot is used with two arguments and if either X or Y has more than one row or column, then

• If Y is a matrix, and x is a vector, plot(x,Y) successively plots the rows or columns of Y versus vector x, using different colors or line types for each. The row or column orientation varies depending on whether the number of elements in x matches the number of rows in Y or the number of columns. If Y is square, its columns are used.

• If X is a matrix and y is a vector, plot(X,y) plots each row or column of X versus vector y. For example, plotting the peaks matrix versus the vector 1:length(peaks) rotates the previous plot.

```y = 1:length(peaks);
plot(peaks,y)
```

• If X and Y are both matrices of the same size, plot(X,Y) plots the columns of X versus the columns of Y.

You can also use the plot function with multiple pairs of matrix arguments.

```plot(X1,Y1,X2,Y2,...)
```

This statement graphs each X-Y pair, generating multiple lines. The different pairs can be of different dimensions.