Thread: SAC Help- Plotpm

Dear Liu Qifan -

There is no way to explicitly adjust axis limits with PLOTXY. The plot limits automatically expland include the full data range.

If you want to restrict the range, a straightforward but slightly complicated way is to write a program to turn your pair of data files into a single XY data file and then plot it with explicit X and Y axis limits.

Another less obvious but simpler way is to use the RGLITCHES THRESHOLD command to set a threshold at the limit that you want to impose. This changes the data in the trace, but will limit the plot values to a desired symmetric range. e.g.

FUNCGEN SEISMOGRAM
WRITE /tmp/seism
CH B 10 ;* shift time origin/phase in memory so the PPM data isn't a line
READ MORE /tmp/seism
RMEAN
RGL TH 1.0 ;* any values |y|>1 set to +1 or -1
XLIM 10 15 ;* just a limit so data same length in each file
PPM

This will get you started and show you the idea.

On 13 Mar 2014, at 02:52, Liu, Qifan wrote:

Hello,

I'm new to SAC but I'm wondering if I could adjust the axis limits of plotpm (particle motion plot)? I selected a small part of data (about 0.01s) and used plotpm. The limits of x, y axes are (-0.7, 1.9), (-0.7, 1.9) respectively. Is there anyway of adjusting these values? I need to fix them at a particular symmetric set of values.

Xlim doesn't appear to work in this case this since it's in fact selecting which part of data the particle motion is based on.

I really appreciate your help,

Qifan
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George Helffrich
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