Matlab：将1x1 sym转换为double

Question

我是MATLAB的新手，我希望将测试（1x1 sym值）转换为double值。

我该怎么做？这是我目前的代码：

function [ xn ] = newton_method( f, x0, h, steps ) 
%f is a symfun 
%x0 is the starting value 
%h is derivation-stepwidth
%steps.. how many calculations 
xn = x0; i = 0; 

while i < steps 
v = f(xn+h)-f(xn); 
derivation = v/h; 
xn = xn - f(xn)/derivation; 
i=i+1; 
output = double(xn) % it returns 1x1 sym and no double
end

Answer 1

我想你想要subs功能。您将符号变量替换为实际值

syms sym_a %a is now a symbolic variable
val_a = subs(sym_a,5.3) % we've replaced the symbolic a with number 5.3