For loop to do 900 subtractions

2022 3 1
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更新时间：2022 3 1
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So I have a Double Difference equation in the form of y = (sqrt(BR^2 - B1^2) - sqrt(BB^2 - B1^2)) - (sqrt(BR^2 - B2^2) - sqrt(BB^2 - B2^2)).......
and so on with B(i) being 901 numbers so (n1 - n2 - n3 - n4 - n5 ....... - n901)
How would I even begin to write a loop to do this so I don't have to cut and paste 901 times?
Please be patient with me my brain is so far gone, i've been at this code for about 100 hours now.
B = [X_mat_base, Y_mat_base, Z_mat_base];
BB = [xyz(1), xyz(2), xyz(3)];
BR = zeros(1, 3);
B = [X_mat_base, Y_mat_base, Z_mat_base];
for i = 1:length(BB(:, 1))
yx(i) = (sqrt(BR(1)^2 - B(i, 1).^2) - sqrt(BB(1)^2 - B(i, 1).^2));
end

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回答（2 个）

Walter Roberson
Walter Roberson 2022-3-1

0 个投票

y = sqrt((BR - B).^2 + (BB - B).^2);

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Terry Poole
Terry Poole 2022-3-1
but thats only the first iteration, i need it to loop through all of B,
y = sqrt((BR - B1).^2 + (BB - B1).^2) - sqrt((BR - B2).^2 + (BB - B2).^2) - sqrt((BR - B3).^2 + (BB - B3).^2) .....
- sqrt(BR- B901).^2 - (BB - B901).^2
Like this.
Terry Poole
Terry Poole 2022-3-1
I'm trying something like this, and I think I'm on the right track.
B = [X_mat_base, Y_mat_base, Z_mat_base];
BB = [xyz(1), xyz(2), xyz(3)];
BR = zeros(1, 3);
for i = 1:length(BB(:, 1))
yx = (sqrt(BR(1)^2 - B(i, 1).^2) - sqrt(BB(1)^2 - B(i, 1).^2));
yx_new = yx...
- (sqrt(BR(1)^2 - B(i+1, 1).^2) - sqrt(BB(1)^2 - B(i+1, 1).^2));
yx = yx_new;
end
Walter Roberson
Walter Roberson 2022-3-1
"and so on with B(i) being 901 numbers so (n1 - n2 - n3 - n4 - n5 ....... - n901)"
That implied to me that you have a single variable named B and that where you wrote B2 in your code you meant B(2) .
If you have individual variables B1, B2, B3, ... B901 then... don't .
http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
David Hill
David Hill 2022-3-1
Your signs are making no sense to me. Your question had all minus signs after the first term. I am confused as to what you want. You should be able to excute without a for-loop. Above some of your BB terms are plus and some are minus

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David Hill
David Hill 2022-3-1

0 个投票

yx=sqrt(BR^2-B(1)^2)-sum(sqrt(BB^2-B.^2))-sum(sqrt(BR^2-B(2:end).^2));

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