Question

菜鸟求教：MATLAB limit用法

>> f=sym('x^2+4*x+10')
>> limit(f,x,a)
??? Undefined function or variable 'x'.
>> limit(f,a)
??? Undefined function or variable 'a'.

应该怎么改啊？谢谢，谢谢~
还有：
>> f=sym('sqrt(1+1/n)');
>> limit(f,n,inf)
??? Undefined function or variable 'n'.

>> int(f,v)
??? Undefined function or variable 'v'.

>> int(f,a,b)
??? Undefined function or variable 'a'.

>> int(f,v,a,b)
??? Undefined function or variable 'v'.

>> f=solve(eq)
??? Error using ==> eq
Not enough input arguments.

Error in ==> eq at 18
[varargout{1:nargout}] = builtin('eq', varargin{:});

>> f=solve(eq,var)
??? Error using ==> eq
Not enough input arguments.

Error in ==> eq at 18
[varargout{1:nargout}] = builtin('eq', varargin{:});

Answer 1

你的变量没有定义。符号计算，要先定义符号变量：syms a b c .....

limit(A,B,C) A:函数 B：待赋值的变量 C：要给变量赋的值

Answer 2

syms x a n %最好这样定义变量
f1=x^2+4*x+10;
limit(f1,x,a)
f2=sqrt(1+1/n);
limit(f2,n,inf)