程序实现画图如y所示,并在图中用红圈标注当y第一次等于0.6的位置
```>> t=0:0.1:2*pi;
y=exp(-0.5*t).*cos(t);
t0=solve(y==0.6,t);
y0=exp(-0.5*t0).*cos(t0);
plot(t,y)
hold on
plot(t0,y0,'or')
text(t0,y0+1,'y=0.6的位置')
错误使用 sym.getEqnsVars>checkVariables (line 92)
Second argument must be a vector of symbolic variables.
出错 sym.getEqnsVars (line 54)
checkVariables(vars);
出错 solve>getEqns (line 429)
[eqns, vars] = sym.getEqnsVars(argv{:});
出错 solve (line 226)
[eqns,vars,options] = getEqns(varargin{:});