> csin := define_external( sin, s::float[8], RETURN::float[8], LIB = "libm.so" );
csin := proc(s::numeric)
option call_external, define_external(sin, s::float[8],
RETURN::float[8], LIB = "libm.so");
    call_external(
    Array(1..8, [...], datatype = integer[4], readonly), false,
    args)
end proc

> csin( evalf( Pi / 2 ) );
                                   1.