From bug-octave-request at bevo dot che dot wisc dot edu  Thu Feb 19 09:36:48 1998
Subject: range input to scripts
From: fabian at olymp dot Umwelt dot TU-Cottbus dot de (Rolf Fabian)
To: bug-octave at bevo dot che dot wisc dot edu
Date: Thu, 19 Feb 1998 16:37:28 +0100

Dear John W.,

the following problem occurred while doing intense work /w octave 
on cygwin32 -platforms. But it seems, that it originates from
general octave-features:

We're tired of typing things like

octave> gset xrange [[ 10:30 []; replot

to the octave-command line under cygwin32.
Note: all square brackets as well as backslashes etc ... must be 
preceeded by a left square bracket on this platform terminal!.
Hence we've written a shorthand-script 'zox.m' (zoom-x-scale without
changing y-scale),  which has 2 input modes, see below.

a) Only the mode mentioned first works, the other where input is a 
   range does not! e.g. 
   octave> zox(1:7)
   error: invalid vector index = 7
   error: evaluating index expression near line XXX column ..
   error: .....

   WHY ?, because
   index = 7 is obviously a valid index of vector-input x=1:7


#----------- CUT HERE -------------------
##usage:  zox(x0,x1)  or  zox(x0:x1) 
##
##zoom gnuplot x-scale to [x0:x1] and replot
##
##see also: zoy (to be developped)
##author: fabian at umwelt dot tu-cottbus dot de 980218

function zox(x0,x1)
	if (nargin !=2)
	   if (nargin==1 && is_vector(x0))
		#if x0 is range or vector: use only first/last element
		x0 = x0(1);
		x1 = x0(length(x));    # <-- XXX
	   else
		fprintf(stderr,"usage: zox(x0,x1) or zox(x0:x1)\n");return;
	   endif
	endif

	axis([x0,x1]);
	replot;       

endfunction
#----------- CUT HERE -------------------


b) We've tried to develop a corresponding counterpart 'zoy.m'
   (zoom-y-scale without changing x-scale), but didn't succeed, 
   because we don't see a way to get the current x-scale status
   (displayed by 'gshow xscale') into a variable, which might be
   transferred to 'axis([x0,x1,y0,y1])'.
   Do you see a way to accomplish that?

   REM:
   IN THE MEANTIME, WE'VE LEARNED FROM THE COMMENTS IN THE SCRIPTS
   INSIDE FOLDER 'PLOT', THAT STATUS-REPORTS OF GNULPLOT's SET-PARAMETERS
   SEEMS TO BE IS A MORE GENERAL PROBELM. Hence forget question b).


Best wishes Rolf Fabian 
980219 fabian at umwelt dot tu-cottbus dot de