all functions - u


 or uncen(ptcen, ireg)  

returns zone centered version of the 2-D zone 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, uncen(ptcen) is equivalent to ptcen(uncp,uncp).  
Do not use uncen to zone center data which is naturally point  
centered -- use the zncen function for that purpose.  The uncen  
function is the (nearly) exact inverse of the ptcen function,  
so that uncen(ptcen(zncen, ireg), ireg) will return the original  
zncen array.  The uncen reconstruction is as exact as possible,  
given the finite precision of floating point operations.  
Interpreted function, defined at i0/std.i   line 3681  

SEE ALSO: ptcen,   zncen  


 or undo3, n  

Undo the effects of the last N (default 1) rot3, orient3, mov3, aim3,  
setz3, or light3 commands.  
Interpreted function, defined at i/pl3d.i   line 608  



 or unit(n, m)  

returns n-by-n (or n-by-m) unit matrix, i.e.- matrix with diagonal  
elements all 1.0, off diagonal elements 0.0  
Interpreted function, defined at i0/matrix.i   line 21  




restores limits to their values before zoom and pan operations  
performed interactively using the mouse.  
Use    old_limits=  limits()  
       limits, old_limits  
to save and restore plot limits generally.  
Builtin function, documented at i0/graph.i   line 913  

SEE ALSO: limits,   range,   zoom_factor,   plg  


    update_mesh, mesh, rt, zt  
 or update_mesh, mesh, rt, zt, ireg  

updates the opaque MESH object to reflect a new RT, ZT, and  
(optionally) IREG.  The boundary edges are recomputed and stored  
in MESH, as well.  
Builtin function, documented at i0/drat.i   line 1086  

SEE ALSO: form_mesh,   integ_flat,   integ_linear  


    file= updateb(filename)  
 or file= updateb(filename, primitives)  

open a binary date file FILENAME for update (mode "r+b").  
The optional PRIMITIVES argument is as for the createb function.  
If the file exists, it is opened as if by openb(filename),  
otherwise a new PDB file is created as if by createb(filename).  
Interpreted function, defined at i0/std.i   line 3063  

SEE ALSO: openb,   createb,   cd,   save,   restore,   get_vars,   get_addrs,   close102,  
close102_default,   open102,   at_pdb_open,   at_pdb_close  



    dummy= use_origins(dont_force)  

Yorick array dimensions have an origin as well as a length.  
By default, this origin is 1 (like FORTRAN arrays, unlike C  
arrays).  However, the array function and the pseudo-index (-)  
can be used to produce arrays with other origins.  
Initially, the origin of an array index is ignored by Yorick; the  
first element of any array has index 1.  You can change this  
default behavior by calling use_origins with non-zero DONT_FORCE,  
and restore the default behavior by calling use_origins(0).  
When the returned object DUMMY is destroyed, either by return from  
the function in which it is a local variable, or by explicit  
redefintion of the last reference to it, the treatment of array  
index origins reverts to the behavior prior to the call to  
use_origins.  Thus, you can call use_origins at the top of a  
function and not worry about restoring the external behavior  
before every possible return (including errors).  
*** DEPRECATED ***  
Do not use index origins.  Your brain will explode sooner or later.  
Builtin function, documented at i0/std.i   line 405  

SEE ALSO: array,   dimsof,   orgsof