a help problem

[Vic Norton]

I am running Homebrew Octave 4.2.0 on an iMac OS X 10.12.1. Everything
works perfectly except this curious test script.

########## begin script #################
% test1.m
%   Why doesn't this message show up when I do
%     octave> help test1
%   unless I remove one % from each of the double-% lines

chdir (fileparts(mfilename("fullpath")));
printf("hello world\n");
load XYTable.mat XY;  % XYTable.mat contains the 2 x 9 lookup table XY

%%{
function y = x2y(XY, x)
y = 0;
i1 = lookup(XY(1, :), x);
if i1 == 0; return; endif
i0 = i1 + 1;
x0 = XY(1, i0); x1 = XY(1, i1);
y0 = XY(2, i0); y1 = XY(2, i1);
y = y0 + (y1 - y0) * ((x - x0) / (x1 - x0));
endfunction  % x2y
x = 27
y = x2y(XY, x)
%%}

%{
% XYTable.mat:
# Created by Octave 4.2.0, Wed Nov 23 16:00:00 2016 EST <address@hidden>
# name: XY
# type: matrix
# rows: 2
# columns: 9
42.4530 35.4921 29.4225 28.3286 26.8788 26.7901 23.3404 22.6220 18.2069
26.5579 16.2450 8.40148 7.51666 6.73955 6.70094 5.21504 4.91929 3.29878
%}
########### end script ################

When I do 
 octave> help test1
I see
 'test1' is a script from the file /Users/vicnorton/...

 x2y

 Additional help for built-in functions …

Executing the script:
 octave> test1
produces
 hello world
 x =  27
 y =  6.8045

If I remove a % from both of the double-% lines and write
 octave> help test1
I get
 'test1' is a script from the file /Users/vicnorton/...

 test1.m
   Why doesn't this message show up when I do
     octave> help test1
   unless I remove one % from each of the double-% lines

  Additional help for built-in functions …

But now executing
 octave> test1
simply produces the line
 hello world

Why do I only get the help-description of the script when I comment out
the x2y function? Something very strange is going on here.

How do I create a lookup function without destroying the functionality
of the leading help-description of my script?

Any suggestions would be much appreciated.

Regards,

Vic

test1.m
Description: Binary data

XYTable.mat
Description: Binary data