Mitch,
Another sac-help user, Januka, has replied and referred you to an earlier message thread. And that may solve your problem.
But, if I understand your problem correctly, you want to save the blackboard values that LINEFIT produces. And that is a bit different from what is in the message thread Januka referred to. Nevertheless, you should read the message thread Januka referred to, since it may help you soon, if not with this particular problem.
Here is a description of header and blackboard variables that may help you do that.
SAC header and SAC blackboard variables are actually two very different places to store information.
SAC header variables can be written into the SAC data file, and thus, be saved. But this is not automatic. You need to give the SAC command ‘writehdr’ (without the ‘') to actually write any new SAC header values out to the SAC data file. Otherwise, those new values will go away when you quit SAC or after you read a new trace into SAC.
SAC blackboard variables are similar to what you might write on a blackboard and are temporary. They go away when you quit SAC.
The entry for LINEFIT in the SAC manual is confusing, since it states that LINEFIT “writes results to header blackboard variables”. I’ve not used LINEFIT, but am familiar with SAC header variables, and I don’t recognize any of the variables referred to in the LINEFIT description (SLOPE, YINT and so on) as SAC header variables.
But, you can use the SAC ‘writebbf' command to write the blackboard variables to a separate file, one that is distinct from the SAC data file. There is another SAC command ‘readbbf' to read blackboard variables from the file.
You should look at the SAC manual for a fuller description of these commands.
Good Luck,
Leigh
On Apr 17, 2019, at 5:15 PM, Mitchell Liddell <liddell<at>ualberta.ca> wrote:
Hello,
I am using LINEFIT to calculate the slope of a particular function in SAC. The process seems to work, but the results are not written into the header like the manual page indicates they should be:
"...the linear fit are written to blackboard variables SLOPE, YINT, SDSLOPE, SDYINT, SDDATA and CORRCOEF respectively.."
In my case I receive an output like:
SAC> r CS.ph
SAC> linefit
Slope and standard deviation are: 0.87509 0.0053469
Intercept and standard deviation are: 0.37646 0.15027
Data standard deviation is: 1.7514
Data correlation coefficient is: 0.9906
But the header variables for SLOPE etc. are all empty. Can you help with this?
Thank you!
Mitch V. Liddell
--
Mitch V. Liddell, PhD
Postdoctoral Researcher
University of Alberta
587-372-5060
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Mitchell Liddell
Leigh House
Geo .
