%!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.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

/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


% end included library code

/toeplitzmatrix {
    9 dict begin
    /a exch def
    /ym a length 1 sub def
    /xm a 0 get length 1 sub def
    /toeplitz true def
    1 xm sub 1 ym 1 sub {
        /xb exch def
        /init true def
        /tv 0 def
        xb 1 xb xm add {
            /x exch def
            x 0 ge x xm le and {
                /y x xb sub def
                y 0 ge y ym le and {
                    init {
                        /init false def
                        /tv a y get x get def
                    } {
                        a y get x get tv ne {
                            /toeplitz false def
                            exit
                        } if
                    } ifelse
                } if
            } if
        } for
        toeplitz not {
            exit
        } if
    } for
    toeplitz
    end
} bind def

(toeplitzmatrix) test.start
[[4 3 2 1] [5 4 3 2] [6 5 4 3]] toeplitzmatrix test
[[1 2 3] [3 2 1]] toeplitzmatrix not test
test.end