xbasc();/// @@prerequisite 
x=linspace(-%pi,%pi,40); y=linspace(-%pi,%pi,40);
plot3d(x,y,sinh(x')*cos(y)) ; /// \sleftarrow{\normalfont an \( \R\sp{3}\) surface (Figure~\ref{f:gr2})}
xs2ps(0,'fig2'); /// @@prerequisite affectations 
unix(SCI+'/bin/BEpsf fig2'); /// @@prerequisite