参考如下例程: / k# V$ m. t$ I, F' ^$ Z>> c = 1.0; 2 l8 {$ n x F+ O' v. g5 m! D>> class(c) ' _* f/ V$ D+ f) E$ vans = $ C' h& ]( M% {$ _# W3 Adouble# z4 x2 x3 @: A' \% `" L5 w+ y
>>a = single(c)' S$ j5 s5 l4 U, E _
a = f% K1 [& `, |: X2 U 1 * u4 U3 b! N/ ^>> class(a)2 M5 t. R: S0 b% t
ans =* d! j* p, V( D, Y o( e# f
single