Source code in the icon programming language

procedure main(A)
    tM := [[  1,  2, -1, -4],
           [  2,  3, -1,-11],
           [ -2,  0, -3, 22]]
    showMat(rref(tM))
end

procedure rref(M)
    lead := 1
    rCount := *\M | stop("no Matrix?")
    cCount := *(M[1]) | 0
    every r := !rCount do {
        i := r
        while M[i,lead] = 0 do {
            if (i+:=1) > rCount then {
                i := r
                if cCount < (lead +:= 1) then stop("can't reduce")
                }
            }
        M[i] :=: M[r]
        if 0 ~= (m0 := M[r,lead]) then every !M[r] /:= real(m0)
        every r ~= (i := !rCount) do {
            every !(mr := copy(M[r])) *:= M[i,lead]
            every M[i,j := !cCount] -:= mr[j]
            }
        lead +:= 1
        }
    return M
end

procedure showMat(M)
    every r := !M do every writes(right(!r,5)||" " | "\n")
end