n(x)

Question

Elias Hassan Rezai 2020-10-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/625468-n-x

评论： Elias Hassan Rezai 2020-10-25

can someboduy tell me wqhat is does these three kind of code mean? I mean why code3 is not working and what dows a( r ) actually mean? hwo does these change the layout? by rthe way this is not a homework but only my own thought :)

CODE1)

a=[0 1]; 
for r=3:100 
    a(r)=(r-1)+(r-2); 
end
disp(a)

CODE2)

a=[0 1]; 
for r=3:100 
    a(r)=a(r-1)+a(r-2); 
end
disp(a) 

CODE3)

a=[0 1]; 
for r=3:100 
    a(r)=a(r-1)+a(r-2); 
end
disp(a)

2 个评论
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Walter Roberson 2020-10-25

? Code 3 is the same as Code 2 and produces the same result.

Elias Hassan Rezai 2020-10-25

I forgot to change that; I meant a=(1) in code 3 :)

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Answer 1

drummer 2020-10-25

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/625468-n-x#answer_523928

编辑：drummer 2020-10-25

在 MATLAB Online 中打开

CODE1)

a=[0 1];                % you tell MATLAB a is a vector
for r=3:100             % the for loop you understand, right?
    a(r)=(r-1)+(r-2);   % you're attributing to the rth term of your vector a values of (r - 1) + (r - 2)
                        % the 1st iteration will be a(3) = (3 - 1) + (3 - 2); a(4) = (4 - 1) + (4 - 2); so on...
end

disp(a)

CODE2)

a=[0 1];                %from this line, a(1) = 0 and a(2) = 1.
for r=3:100 
    a(r)=a(r-1)+a(r-2); % the difference between this and code 1) is that you're performing
                        % the summation calling the indexes in the vector a, rather than r values.
                        % so a(3) = a(2) + a(1) = 0 + 1 = 1
                        % In code 1, a(3) = 2 + 1 = 3
end
disp(a)