%@AUTEUR: Juergen Gilg
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\defFunction[algebraic]{klein}(u,v){cos(u)*cos(v)*(abs(cos(7*v/4))^1.7 + 
    abs(sin(7*v/4))^1.7)^(-1/0.2)*(abs(cos(7*u/4))^1.7 + 
    abs(sin(7*u/4))^1.7)^(-1/0.2)}%
{sin(u)*(abs(cos(7*u/4))^1.7 + abs(sin(7*u/4))^1.7)^(-1/0.2)}%
{cos(u)*sin(v)*(abs(cos(7*v/4))^1.7 + 
    abs(sin(7*v/4))^1.7)^(-1/0.2)*(abs(cos(7*u/4))^1.7 + 
    abs(sin(7*u/4))^1.7)^(-1/0.2)}
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    fillcolor=green,
    ngrid=60,
    %RotY=90,
    RotX=-90,
    function=klein]%
}
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