%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/test.start {
    print (:) print
    /test.pass 0 def
    /test.count 0 def
} bind def

/test {
    /test.count test.count 1 add def
    {
        /test.pass test.pass 1 add def
    } {
        ( ) print
        test.count (....) cvs print
        (-fail) print
    } ifelse
} bind def

/test.end {
    ( ) print
    test.count 0 gt {
        (Passed ) print
        test.pass (...) cvs print
        (/) print
        test.count (...) cvs print
        ( \() print
        test.pass 100 mul test.count idiv (...) cvs print
        (%\)) print
        (\r\n) print
    } if
} bind def


% end included library code

/maxdiff {
    0 dict begin
    /a exch def
    0
    0 1 a length 2 sub {
        /w exch def
        w 1 add 1 a length 1 sub {
            /x exch def
            w 1 add 1 a length 2 sub {
                /y exch def
                x y ne {
                    y 1 add 1 a length 1 sub {
                        /z exch def
                        z x ne {
                            a w get a x get mul a y get a z get mul sub abs
                            max
                        } if
                    } for
                } if
            } for
        } for
    } for
    end
} bind def

(maxdiff) test.start
[5 9 3 4 6] maxdiff 42 eq test
[1 -2 3 -4] maxdiff 10 eq test
[-3 -1 -2 -4] maxdiff 10 eq test
[10 2 0 5 1] maxdiff 50 eq test
[7 8 9 10 10] maxdiff 44 eq test
test.end