all functions - z


    crc32 = z_crc32(crc32, data)  
 or adler32 = z_crc32(adler32, data, 1)  

Compute the crc32 or adler32 checksum of DATA.  The first  
argument can be [] (nil) if this is the first chunk of DATA;  
to checksum a long stream of data you can call z_crc32 on  
a series of chunks, feeding the result of each call as input  
to the following call.  
   Builtin function, documented at i0/zlib.i   line 132  

SEE ALSO: z_setdict  


    buffer = z_deflate()  
 or buffer = z_deflate(level)  
 or buffer = z_deflate(level, dictionary)  

    then navail = z_deflate(buffer, data)  
      or zdata = z_flush(buffer)  
 finally zdata = z_flush(buffer, data)  
      or zdata = z_flush(buffer, -)  
In any of the first three forms, initiate a zlib deflation  
BUFFER.  The second two forms allow you to specify a compression  
LEVEL (0-9 in increasing compression and decreasing speed), and/or  
a special compression DICTIONARY (which you will need to supply  
again in order to decompress the data later).  
After the BUFFER has been created, use z_deflate to compress DATA,  
adding it to the compressed stream in the BUFFER.  After one or  
several calls to z_deflate, you can call z_flush in the first form  
to extract the current BUFFER contents as ZDATA, the portion of  
the compressed data stream stored in BUFFER.  You can alternate  
calls to z_deflate and z_flush as many times as you like in order  
to compress an arbitrary amount of DATA into ZDATA without filling  
memory.  The NAVAIL returned by z_deflate is a lower limit on the  
number of bytes of compressed data a subsequent z_flush will return.  
The final block of DATA must be compressed by a call to z_flush,  
in the final form.  This flushes all remaining data into the  
resulting ZDATA and closes the BUFFER.  You can call z_flush  
in this form immediately after creating the buffer, so that  
the tersest way to compress a single block of data is:  
       zdata = z_flush(z_deflate(), data)  
Use - for DATA to indicate you have no more DATA, but want to  
finish the compression.  
   Builtin function, documented at i0/zlib.i   line 13  

SEE ALSO: z_inflate,   z_flush,   z_crc32  


    zdata_or_data = z_flush(buffer)  
 or zdata = z_flush(buffer, data)  
 or zdata = z_flush(buffer, -)  
 or data = z_flush(buffer, type)  

Flushes all available ZDATA (if STATE is a z_deflate state) or  
all available DATA (if STATE is a z_inflate state).  For z_deflate  
states, a second argument to z_flush is the final DATA block to  
complete the ZDATA stream.  For z_inflate states, you may specify  
an array data TYPE so that the return DATA value will have that  
data type instead of char.  
   Builtin function, documented at i0/zlib.i   line 96  

SEE ALSO: z_deflate,   z_inflate,   z_setdict  


    buffer = z_inflate()  

    then flag = z_inflate(buffer, zdata)  
      or flag = z_inflate(buffer, zdata, data)  
      or data = z_flush(buffer)  
      or data = z_flush(buffer, type)  
In the first form, initiate a zlib inflation BUFFER.  You use  
that BUFFER in subsequent calls to z_inflate if you do not know  
in advance how large the uncompressed DATA will be, or if you  
want to do the decompression in chunks to conserve memory.  
Use the second or third forms to actually decompress ZDATA.  
After one or more calls to z_inflate, you can call z_flush in  
order to extract whatever uncompressed DATA has so far been  
produced.  You can optionally specify a TYPE array for  
z_flush, otherwise the DATA will be a 1D array of char.  
Alternatively, you can supply a DATA array as the third parameter  
to z_inflate, in which case z_inflate will uncompress to your DATA  
array instead of to an internal array in BUFFER.  You can use this  
form if you already know the size and data type the data will  
decompress to.  If the returned flag is 3, you can call z_setdict  
and repeat the call.  Otherwise, a return value other than 0  
probably represents an error.  Note that z_flush will not return  
bytes that have been written to a DATA array supplied to z_inflate.  
The FLAG returned by z_inflate is  
  0  if the ZDATA stream is complete, in which case no  
     further calls to z_inflate are legal with that BUFFER  
     - the next call to z_flush will return all remaining  
       bytes of the uncompressed data  
  1  if the ZDATA stream is incomplete, but no additional  
     uncompressed data is yet available in BUFFER  
  2  if the ZDATA stream is incomplete, and uncompressed data  
     can be retrieved from BUFFER by calling z_flush  
  3  if a DICTIONARY is required to continue decompression  
     - use z_setdict to set a dictionary and call z_inflate  
       a second time with the same DATA  
 -1  if the ZDATA stream completed, but contained additional  
     bytes after the end  
 -2  if the ZDATA stream is corrupted  
   Builtin function, documented at i0/zlib.i   line 50  

SEE ALSO: z_deflate,   z_flush,   z_setdict,   z_crc32  


    adler32 = z_setdict(buffer)  
 or flag = z_setdict(buffer, dictionary)  

In the first form, returns the adler32 checksum of the dictionary  
required to continue decompressing a stream after z_inflate  
returns 3, or [] (nil) if BUFFER does not need a dictionary.  
You can also use this form to retrieve the adler32 checksum of  
a dictionary you supplied in the call to z_deflate that  
returned BUFFER.  
In the second form, sets the DICTIONARY for BUFFER so that  
succeeding calls to z_inflate can continue decompressing.  The  
return value FLAG is 1 on success, or 0 on failure.  
You can compute the adler32 checksum using the z_crc32 function.  
   Builtin function, documented at i0/zlib.i   line 112  

SEE ALSO: z_inflate,   z_crc32  


 or zncen(ptcen, ireg)  

returns zone centered version of the 2-D point centered array PTCEN.  
The result is (imax-1)-by-(jmax-1) if PTCEN is imax-by-jmax.  
If the region number array IREG is specified, zones with region  
number 0 are not included in the point centering operation.  
Note that IREG should have dimensions imax-by-jmax, like  
the input PTCEN array; the first row and column of IREG are ignored.  
Without IREG, zncen(ptcen) is equivalent to ptcen(zcen,zcen).  
Interpreted function, defined at i0/std.i   line 3662  

SEE ALSO: ptcen,   uncen  


    zoom_factor, factor  

sets the zoom factor for mouse-click zoom in and zoom out operations.  
The default FACTOR is 1.5; FACTOR should always be greater than 1.0.  
Builtin function, documented at i0/graph.i   line 906  

SEE ALSO: limits,   range,   unzoom,   plg  



returns the vector of (complex) roots of the (complex)   
polynomial: Sum(a(i)*x^(i-1)) using Laguerre's method.  
The roots are sorted in order of increasing real parts.  Call with  
non-zero imsort keyword to sort into increasing imaginary parts.  
See Numerical Recipes (Press, et. al., Cambridge Univ. Press 1988),  
section 9.5.  
Interpreted function, defined at i/zroots.i   line 10