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# all functions - u

 uage ``` univAge(z,q0=,lambda0=) Compute the term to integrate to compute the age of the univers. z can be a VECTOR of values. KEYWORDS: q0 : Deceleration parameter,numeric scalar -a*(a'')/(a')^2 (Omega_m/2-lambda0) lambda0 : Cosmological constant, normalized to th closure density. interpreted function, defined at contrib/cosmo.i line 133 ``` SEE ALSO: lumdist

 uncen ``` uncen(ptcen) 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 2898 ``` SEE ALSO: ptcen,   zncen

 uncp38 ``` uncp38 interpreted function, defined at i/test1.i line 335 ```

 undo3 ``` undo3 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 ```

 undup_names ``` undup_names interpreted function, defined at i/make.i line 468 ```

 unit ``` unit(n) 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 ```

 univAge ``` univAge(z,h0=,k=,lambda0=,Omega_m=,q0=,silent=) See IDL routine... PURPOSE: Calculate age of the universe in s EXPLANATION: The luminosity distance in the Friedmann-Robertson-Walker model is taken from Caroll, Press, and Turner (1992, ARAA, 30, 499), p. 511 Uses a closed form (Mattig equation) to compute the distance when the cosmological constant is zero. Otherwise integrates the function using simpson_cosmo. EXAMPLE: Plot the distance of a galaxy in Mpc as a function of redshift out to z = 5.0, assuming the default cosmology (Omega_m=0.3, Lambda = 0.7, H0 = 70 km/s/Mpc) z = span(0,5,50); plg,lumdist(z),z; xytitles,"z","Distance (Mpc)" interpreted function, defined at contrib/cosmo.i line 215 ``` SEE ALSO: ldist

 unzoom ``` unzoom 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 850 ``` SEE ALSO: limits,   range,   zoom_factor,   plg

 update_mesh ``` 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 1084 ``` SEE ALSO: form_mesh,   integ_flat,   integ_linear

 updateb ``` 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 2294 ``` SEE ALSO: openb,   createb,   cd,   save,   restore,   get_vars,   get_addrs,   close102,   close102_default,   open102,   at_pdb_open,   at_pdb_close

 use_origins ``` 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). builtin function, documented at i0/std.i line 362 ``` SEE ALSO: array,   dimsof,   orgsof