doc: Ensure documentation lists output argument when it exists for all m-files. For new users of Octave it is best to show explicit calling forms in the documentation and to show a return argument when it exists. * bp-table.cc, shift.m, accumarray.m, accumdim.m, bincoeff.m, bitcmp.m, bitget.m, bitset.m, blkdiag.m, celldisp.m, cplxpair.m, dblquad.m, flip.m, fliplr.m, flipud.m, idivide.m, int2str.m, interpft.m, logspace.m, num2str.m, polyarea.m, postpad.m, prepad.m, randi.m, repmat.m, rng.m, rot90.m, rotdim.m, structfun.m, triplequad.m, uibuttongroup.m, uicontrol.m, uipanel.m, uipushtool.m, uitoggletool.m, uitoolbar.m, waitforbuttonpress.m, help.m, __additional_help_message__.m, hsv.m, im2double.m, im2frame.m, javachk.m, usejava.m, argnames.m, char.m, formula.m, inline.m, __vectorize__.m, findstr.m, flipdim.m, strmatch.m, vectorize.m, commutation_matrix.m, cond.m, cross.m, duplication_matrix.m, expm.m, orth.m, rank.m, rref.m, trace.m, vech.m, cast.m, compare_versions.m, delete.m, dir.m, fileattrib.m, grabcode.m, gunzip.m, inputname.m, license.m, list_primes.m, ls.m, mexext.m, movefile.m, namelengthmax.m, nargoutchk.m, nthargout.m, substruct.m, swapbytes.m, ver.m, verLessThan.m, what.m, fminunc.m, fsolve.m, fzero.m, optimget.m, __fdjac__.m, matlabroot.m, savepath.m, campos.m, camroll.m, camtarget.m, camup.m, camva.m, camzoom.m, clabel.m, diffuse.m, legend.m, orient.m, rticks.m, specular.m, thetaticks.m, xlim.m, xtickangle.m, xticklabels.m, xticks.m, ylim.m, ytickangle.m, yticklabels.m, yticks.m, zlim.m, ztickangle.m, zticklabels.m, zticks.m, ellipsoid.m, isocolors.m, isonormals.m, stairs.m, surfnorm.m, __actual_axis_position__.m, __pltopt__.m, close.m, graphics_toolkit.m, pan.m, print.m, printd.m, __ghostscript__.m, __gnuplot_print__.m, __opengl_print__.m, rotate3d.m, subplot.m, zoom.m, compan.m, conv.m, poly.m, polyaffine.m, polyder.m, polyint.m, polyout.m, polyreduce.m, polyvalm.m, roots.m, prefdir.m, prefsfile.m, profexplore.m, profexport.m, profshow.m, powerset.m, unique.m, arch_rnd.m, arma_rnd.m, autoreg_matrix.m, bartlett.m, blackman.m, detrend.m, durbinlevinson.m, fftconv.m, fftfilt.m, fftshift.m, fractdiff.m, hamming.m, hanning.m, hurst.m, ifftshift.m, rectangle_lw.m, rectangle_sw.m, triangle_lw.m, sinc.m, sinetone.m, sinewave.m, spectral_adf.m, spectral_xdf.m, spencer.m, ilu.m, __sprand__.m, sprand.m, sprandn.m, sprandsym.m, treelayout.m, beta.m, betainc.m, betaincinv.m, betaln.m, cosint.m, expint.m, factorial.m, gammainc.m, gammaincinv.m, lcm.m, nthroot.m, perms.m, reallog.m, realpow.m, realsqrt.m, sinint.m, hadamard.m, hankel.m, hilb.m, invhilb.m, magic.m, pascal.m, rosser.m, toeplitz.m, vander.m, wilkinson.m, center.m, corr.m, cov.m, discrete_cdf.m, discrete_inv.m, discrete_pdf.m, discrete_rnd.m, empirical_cdf.m, empirical_inv.m, empirical_pdf.m, empirical_rnd.m, kendall.m, kurtosis.m, mad.m, mean.m, meansq.m, median.m, mode.m, moment.m, range.m, ranks.m, run_count.m, skewness.m, spearman.m, statistics.m, std.m, base2dec.m, bin2dec.m, blanks.m, cstrcat.m, deblank.m, dec2base.m, dec2bin.m, dec2hex.m, hex2dec.m, index.m, regexptranslate.m, rindex.m, strcat.m, strjust.m, strtrim.m, strtrunc.m, substr.m, untabify.m, __have_feature__.m, __prog_output_assert__.m, __run_test_suite__.m, example.m, fail.m, asctime.m, calendar.m, ctime.m, date.m, etime.m: Add return arguments to @deftypefn macros where they were missing. Rename variables in functions (particularly generic "retval") to match documentation. Rename some return variables for (hopefully) better clarity (e.g., 'ax' to 'hax' to indicate it is a graphics handle to an axes object).

--- a/scripts/miscellaneous/cast.m	Wed Mar 30 17:30:18 2022 -0700
+++ b/scripts/miscellaneous/cast.m	Wed Mar 30 20:40:27 2022 -0700
@@ -24,16 +24,16 @@
 ########################################################################
 
 ## -*- texinfo -*-
-## @deftypefn  {} {} cast (@var{val}, "@var{type}")
-## @deftypefnx {} {} cast (@var{val}, "@var{like}", @var{var})
-## Convert @var{val} to data type @var{type}.
+## @deftypefn  {} {@var{y} =} cast (@var{x}, "@var{type}")
+## @deftypefnx {} {@var{y} =} cast (@var{x}, "@var{like}", @var{var})
+## Convert @var{x} to data type @var{type}.
 ##
-## The input @var{val} may be a scalar, vector, or matrix of a class that is
+## The input @var{x} may be a scalar, vector, or matrix of a class that is
 ## convertible to the target class (see below).
 ##
-## If a variable @var{var} is specified after @qcode{"like"}, @var{val} is
+## If a variable @var{var} is specified after @qcode{"like"}, @var{x} is
 ## converted to the same data type and sparsity attribute.  If @var{var} is
-## complex, @var{val} will be complex, too.
+## complex, @var{x} will be complex, too.
 ##
 ## @var{var} may be and @var{type} may name any of the following built-in
 ## numeric classes:
@@ -55,7 +55,7 @@
 ## @end group
 ## @end example
 ##
-## The value @var{val} may be modified to fit within the range of the new type.
+## The value @var{x} may be modified to fit within the range of the new type.
 ##
 ## Examples:
 ##
@@ -68,7 +68,7 @@
 ## @end group
 ## @end example
 ##
-## Programming Note: This function relies on the object @var{val} having a
+## Programming Note: This function relies on the object @var{x} having a
 ## conversion method named @var{type}.  User-defined classes may implement only
 ## a subset of the full list of types shown above.  In that case, it may be
 ## necessary to call cast twice in order to reach the desired type.
@@ -84,7 +84,7 @@
 ## double, single, logical, char, class, typeinfo}
 ## @end deftypefn
 
-function retval = cast (val, type, var)
+function y = cast (x, type, var)
 
   if (nargin < 2 || nargin > 3)
     print_usage ();
@@ -105,8 +105,8 @@
     print_usage ();
   endif
 
-  if (! isnumeric (val) && ! islogical (val) && ! ischar (val))
-    error ("cast: type conversion from '%s' is not supported", class (val));
+  if (! isnumeric (x) && ! islogical (x) && ! ischar (x))
+    error ("cast: type conversion from '%s' is not supported", class (x));
   endif
 
   if (! any (strcmp (type, {"int8"; "uint8"; "int16"; "uint16"; "int32";
@@ -115,17 +115,17 @@
     error ("cast: type conversion to '%s' is not supported", type);
   endif
 
-  retval = feval (type, val);
+  y = feval (type, x);
 
   if (is_like)
-    if (issparse (var) && ! issparse (retval))
-      ## retval is of the same type as var, so it must be convertible to sparse
-      retval = sparse (retval);
-    elseif (! issparse (var) && issparse (retval))
-      retval = full (retval);
+    if (issparse (var) && ! issparse (y))
+      ## y is of the same type as var, so it must be convertible to sparse
+      y = sparse (y);
+    elseif (! issparse (var) && issparse (y))
+      y = full (y);
     endif
-    if (iscomplex (var) || iscomplex (val))
-      retval = complex (retval);
+    if (iscomplex (var) || iscomplex (x))
+      y = complex (y);
     endif
   endif