Thread: sacio.a data size

Started: 2007-08-02 04:53:00
Last activity: 2007-08-02 16:17:48
Topics: SAC Help
John D. West
2007-08-02 04:53:00
Hi.

I'm coding in C on Linux, using the sacio.a library. How can I tell the
length of the data section of a sac file? I thought it was supposed to
be in the NPTS header, but if I try to read with an undersize array,
NPTS returns the array size, not the data size.

Example: I have a file with 25000 data points. Not knowing the size in
advance, I size the array as float fData[10000]. Using the syntax on
the web site to call rsac1( kname, yarray, &nlen, &beg, &del, &max,
&nerr, strlen( kname ) ) ; I provide fData[10000] as yarray and 10000 as
max. When I read the NPTS header, it is 10000, as is the nlen and max
variables. nerr returns 0, not -803 as documented for "number of points
in file is greater than max."

This gives me no way I can find to actually determine the size of the
data segment. What am I doing wrong, and/or how do I work around this
problem?

Thanks!

-- John



  • Brian Savage
    2007-08-02 16:17:48
    John

    Thanks for the reporting of this.

    Which version of the SAC are you using ?
    And would you send me an example code of the problem
    so I can track down the bug.

    Cheers,
    Brian


    On Aug 1, 2007, at 11:53 PM , John D. West wrote:

    Hi.

    I'm coding in C on Linux, using the sacio.a library. How can I
    tell the length of the data section of a sac file? I thought it
    was supposed to be in the NPTS header, but if I try to read with an
    undersize array, NPTS returns the array size, not the data size.

    Example: I have a file with 25000 data points. Not knowing the
    size in advance, I size the array as float fData[10000]. Using
    the syntax on the web site to call rsac1( kname, yarray, &nlen,
    &beg, &del, &max, &nerr, strlen( kname ) ) ; I provide fData[10000]
    as yarray and 10000 as max. When I read the NPTS header, it is
    10000, as is the nlen and max variables. nerr returns 0, not -803
    as documented for "number of points in file is greater than max."

    This gives me no way I can find to actually determine the size of
    the data segment. What am I doing wrong, and/or how do I work
    around this problem?

    Thanks!
    -- John

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