Removing a syms variable from a For loop solution

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Jonathan Hiew
Jonathan Hiew 2019-3-14
回答： Agnish Dutta 2019-3-20
Hello there, I am trying to create a for loop function for a simple formula that includes differentiationCapture.JPG but I am getting the solution :
ans =
[ x, -2510341221049253/4503599627370496, 296951380318845/4503599627370496, -3448745601629/36028797018963968, 21572111/73786976294838206464, 0, 0]
which is correct but is there a way to remove the x? Here is my code. Any help is greatly appreciated!
function x = newton3(Func, x1, N)
syms x
F(x) = diff(Func(x));
%apply Newton's Method
a=Func(x1);
b=double(F(x1));
d = x1 - (a/b);
%apply Newton's Method
%ans=[;];
for i=1:N
syms x;
F(x) = diff(Func(x));
a=Func(x1);
b=double(F(x1));
c=a/b;
d(i) = x1 - c;
x=[x,d];
x1=d(i);
%ans=[ans;x1];
%iterate through Newton's method N times and store results in vector
end

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回答（1 个）

Agnish Dutta
Agnish Dutta 2019-3-20
Based on on the provided equation and code, here's something I came up with to calculate the neede values:
syms x
N = 100 % No. of itereations.
% I've taken a sample function to demonstrate. Simply replace the RHS of f(x) with your desired function.
f(x) = 5*x^2 - 3*x + 7;
f_prime(x) = diff(f(x));
x_init = f(0) / f_prime(0);
% An array to hold intermediate and the final values.
vals = [];
vals(1) = x_init;
% Loop to calculate the values in each iteration.
for i = 2:N
vals(i) = vals(i - 1) + f(i) / f_prime(i);
end
If however, you wish to keep the rest of your code intact and just remove the first element from the array that stores your result:
ans = ans(2: end)

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