The default mode of plotting is to use the minimum and maximum values of the data to determine appropriate axis ranges. An exception occurs if the dependent variable data are all positive. In this case, the minimum Y value is considered to be zero (this can be inhibited; see Tables 6.4 and 6.5).

The system variables that restrict the plot range in the X and Y directions are !X.RANGE and !Y.RANGE respectively. These are two-element vectors with the first element containing the minimum value and the second element containing the maximum value. Once they are set, plots will continue to be scaled accordingly until they are changed. To restore autoscaling, set !X.RANGE and/or !Y.RANGE to [0,0].

Ranges can be specified for individual plots without changing the settings of !X.RANGE and !Y.RANGE. See Table 6.5 for examples.

PLOT,x,y,/ynozero | Cause minimum of Y axis to be data minimum instead of zero for this plot. |

!x.range=[2790,2810] | Restrict all subsequent plots to X axis values between 2790 and 2810. |

!y.range=[-1e-13,1e-13] | Restrict all subsequent plots to Y axis values between -1e-13 and 1e-13. |

PLOT,x,y,xrange=[1400,1500] | Restrict the current plot only to X axis values between 1400 and 1500. |

PLOT,x,y,yrange=[0,0] | For this plot only, use autoscaling on the Y axis. |