按你的语句 运行完的结果和你说的不一样：
s3 =
-.32117320644214174679478487023195
.32117320644214174679478487023195
x3 =
-.22999275816638841028516780789997+.15000000000000000000000000000000*(-3.-16.*sin(x3)^2+16.*sin(x3))^(1/2)
.22999275816638841028516780789997+.15000000000000000000000000000000*(-3.-16.*sin(x3)^2+16.*sin(x3))^(1/2)
x4 =
-1.9641858908552267692932569383891
1.1774067627345664691693864448904
se =
-1.*asin(4.*sin(x3)-2.)
-1.*asin(4.*sin(x3)-2.)
第一条语句写不写都无所谓吧，本来用solve解出来的就是符号解，就不需要再把s3,x3,x4,se定义成符号，而且syms s3,x3,x4,se;的逗号应该换成空格。
