Taylor series of log(x) with a = 1.

Question

Ibrahima Diallo 2019-9-3

0
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回答： Kritika Bansal 2019-9-13

How to Write a Matlab function that sums up a specified number of terms from the Taylor series of log(x) with a = 1.

%I need my own sript.
%I tried this: 
function s = etaylor_log(x, n)
 syms x
s = taylor(log(x), 'ExpansionPoint', 1, 'Order', n+1)
 end
% It does not give values. 
% The second : 
function s = etaylor_log(x, n)
for i=1:n;
 
    y(i) = (x-1).^(i-1)*(x-1).^i/i;
 
end
s=sum(y);
% it does not show for n=0.

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Ibrahima Diallo 2019-9-3

在 MATLAB Online 中打开

%I need my own sript.
%I tried this: 
function s = etaylor_log(x, n)
 syms x
s = taylor(log(x), 'ExpansionPoint', 1, 'Order', n+1)
 end
% It does not give values. 
% The second : 
function s = etaylor_log(x, n)
for i=1:n;
 
    y(i) = (x-1).^(i-1)*(x-1).^i/i;
 
end
s=sum(y);
% it does not show for n=0.

Walter Roberson 2019-9-4

When n is 0 then for i=1:n will not execute at all, so you will not create the variable y

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Answer 1

Kritika Bansal 2019-9-13

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/478759-taylor-series-of-log-x-with-a-1#answer_391665

在 MATLAB Online 中打开

Hi,

Taking the analogy from the expression returned by the following command:

taylor(log(x), x, 'ExpansionPoint', 1, 'Order', n);

You can design your script as follows:

function s = etaylor_log(x, n)
    if n==0
        error("The value of order can only be a positive integer i.e. n>0");
    end 
    if n == 1
        s = 0;
        return;
    end
    for i=1:n-1
        y(i) = ((x-1).^(i)*(-1).^(i-1))/i;
    end
    s=sum(y);
end