iteration using for loop is not working
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a(1)=0;
b(1)=1;
c(1)=0;
n=1;
for n=1:5
a(2)=0.5*(a(1)-b(1));
b(2)=0.5*((a(1))-(b(1))-(a(1)*c(1)));
c(2)=0.5*((a(1)*b(1)-c(1)));
a(1)=a(2);
b(1)=b(2);
c(1)=c(2);
n=n+1;
end
disp(a(2))
how to run this program to give from old value to new value using iteration a(2) giving more than five value
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Respuestas (1)
Image Analyst
el 6 de Mzo. de 2022
Try it like this:
numElements = 5;
a = zeros(1, numElements);
b = ones(1, numElements);
c = zeros(1, numElements);
for n = 2 : numElements
a(n) = 0.5*(a(n-1)-b(n-1));
b(n) = 0.5*((a(n-1))-(b(n-1))-(a(n-1)*c(n-1)));
c(n) = 0.5*((a(n-1)*b(n-1)-c(n-1)));
end
a
b
c
10 comentarios
Walter Roberson
el 6 de Mzo. de 2022
numElements = 20;
a = sym(zeros(1, numElements));
b = sym(ones(1, numElements));
c = sym(zeros(1, numElements));
for n = 2 : numElements
a(n) = (1/sym(n))*10*(a(n-1)-b(n-1));
b(n) = (1/sym(n))*((28*a(n-1))-(b(n-1))-(a(n-1)*c(n-1)));
c(n) = (1/sym(n))*((a(n-1)*b(n-1)-3.3*c(n-1)));
end
a
b
c
digits(10)
vpa(a)
vpa(b)
vpa(c)
Walter Roberson
el 6 de Mzo. de 2022
Editada: Walter Roberson
el 6 de Mzo. de 2022
numElements = 10;
syms a [1 numElements]
syms b [1 numElements]
syms c [1 numElements]
for n = 2 : numElements
a(n) = (1/sym(n))*10*(a(n-1)-b(n-1));
b(n) = (1/sym(n))*((28*a(n-1))-(b(n-1))-(a(n-1)*c(n-1)));
c(n) = (1/sym(n))*((a(n-1)*b(n-1)-3.3*c(n-1)));
end
Ea = expand(a);
Ca = vpa(findSymType(Ea, 'number'),5);
[~, idx] = sort(abs(Ca), 'desc');
format long g
double(reshape(Ca(idx(1:10)),[],1))
So by the time you get to 10, you are working with coefficients as large as 2*10^24
Ca0 = vpa(findSymType(expand(subs(Ea, [sym('a1'), sym('a3')], [0,0])),'number'),5);
[~, idx] = sort(abs(Ca0), 'desc');
double(reshape(Ca0(1:10), [], 1))
And after you take into account that a and c start out as 0, you are still working with coefficients in the 10^18 range by the time you get to numElements = 10.
It isn't MATLAB messing up: your formulas are not working out for b as large as 1. If b were less than 1, then you might get very different results.
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