[SAC-HELP] sacio.a data size

[John D. West]

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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