Thread: Do Loop Bug

Started: 2008-10-09 05:51:12
Last activity: 2008-10-09 21:55:13
Topics: SAC Help
Bob Hancock
2008-10-09 05:51:12
I copied the Do Loop macro for particle motion plots from the Do Loop
Examples contained in the MACRO Section of the SAC Manual, and have found a
problem ­ See Macro followed by explanation below:

READ ABC
SETBB TIME1 0
DO TIME2 FROM 2 TO 10 BY 2
XLIM %TIME1 $TIME2
TITLE 'Particle Motion from %TIME1 to $TIME2$'
PLOTPM
SETBB TIME1 $TIME2
ENDDO

There are four variables in the macro

Time1 ­ The starting value for XLIM
Time2 ­ The ending value for XLIM
Upper limit of macro processing
Incremental value to increase or decrease the values of both Time1 and Time2
for the next increment.

As long as the incremental value is equal to or greater than the time
difference between Time1 and Time2, the macro works as advertised. NOTE ­
This is how the Macro above is setup.

However, when the incremental time is decreased to less than the value
between Time1 and Time2, the time difference between Time1 and Time two is
AUTOMATICALLY decreased to equal the incremental value. See values in Macro
below:

READ ABC
SETBB TIME1 2300
DO TIME2 FROM 2400 TO 2800 BY 5
XLIM %TIME1 $TIME2
TITLE 'Particle Motion from %TIME1 to $TIME2$'
PLOTPM
SETBB TIME1 $TIME2
ENDDO

I have not found a solution to this problem.

If anyone has encountered this problem, or has a suggestion on how to
alleviate the problem, I would appreciate hearing from them.

Thank You

Bob Hancock

  • George Helffrich
    2008-10-09 21:55:13
    Dear All -

    It is a feature-cum-bug in SAC's implementation of DO that all the
    numeric values are generated as a single string upon entry to the loop.
    If there are many values (80 in your case) that's a long string and it
    can get truncated or overflow. Here's a workaround that uses
    SYSTEMCOMMAND to build a file of macro invocations for each time
    window. Beware of all the "@"-escapes:

    funcgen seismogram; w /tmp/hold0; w /tmp/hold1; r /tmp/hold0 /tmp/hold1
    sc echo xlim @$1 @$2 > /tmp/macro
    sc echo title 'Particle Motion from @$1 to @$2@$' >> /tmp/macro
    sc echo plotpm >> /tmp/macro
    sc echo 2400 2800 5 | awk '{for@(t=@$1;t<=@$2;t+=@$3@) printf "m
    /tmp/macro @%f @%f\n",t,t+100}' > /tmp/sac.in
    sc rm -f /tmp/macro /tmp/sac.in

    On 9 Oct 2008, at 06:51, Bob Hancock wrote:

    I copied the Do Loop macro for particle motion plots from the Do Loop
    Examples contained in the MACRO Section of the SAC Manual, and have
    found a problem – See Macro followed by explanation below:

    READ ABC
    SETBB TIME1 0
    DO TIME2 FROM 2 TO 10 BY 2
    XLIM %TIME1 $TIME2
    TITLE 'Particle Motion from %TIME1 to $TIME2$'
    PLOTPM
    SETBB TIME1 $TIME2
    ENDDO

    There are four variables in the macro

    Time1 – The starting value for XLIM
    Time2 – The ending value for XLIM
    Upper limit of macro processing
    Incremental value to increase or decrease the values of both Time1
    and Time2 for the next increment.

    As long as the incremental value is equal to or greater than the time
    difference between Time1 and Time2, the macro works as advertised.
    NOTE – This is how the Macro above is setup.

    However, when the incremental time is decreased to less than the
    value between Time1 and Time2, the time difference between Time1 and
    Time two is AUTOMATICALLY decreased to equal the incremental value.
    See values in Macro below:

    READ ABC
    SETBB TIME1 2300
    DO TIME2 FROM 2400 TO 2800 BY 5
    XLIM %TIME1 $TIME2
    TITLE 'Particle Motion from %TIME1 to $TIME2$'
    PLOTPM
    SETBB TIME1 $TIME2
    ENDDO

    I have not found a solution to this problem.

    If anyone has encountered this problem, or has a suggestion on how to
    alleviate the problem, I would appreciate hearing from them.

    Thank You

    Bob Hancock _______________________________________________
    sac-help mailing list
    sac-help<at>iris.washington.edu
    http://www.iris.washington.edu/mailman/listinfo/sac-help

    George Helffrich
    george<at>geology.bristol.ac.uk

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