How to Substitute an array into an equation and solve it ?
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So if i had a = [1 2 3] b = [4 5 6] c = [7 8 9]
and the equation is ax^2+bx+c = 0
How would i substitude the array and solve for x ?
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Ameer Hamza
2020년 11월 15일
편집: Ameer Hamza
2020년 11월 15일
For the given value of a, b, and c, the equation have no real solutions. Following shows how to use fsolve() when the equations have solutions
a = [1 2 3];
b = [4 5 6];
c = [-7 -8 -9];
F = @(x) a(:).*x.^2+b(:).*x+c(:);
sol = fsolve(F, rand(3,1))
If you don't have optimization toolbox, then you can use fzero()
a = [1 2 3];
b = [4 5 6];
c = [-7 -8 -9];
sol = zeros(size(a));
for i=1:numel(a)
F = @(x) a(i).*x.^2+b(i).*x+c(i);
sol(i) = fzero(F, rand());
end
댓글 수: 2
Ameer Hamza
2020년 11월 15일
No, you are not using subs() correct. Following shows how it needs to be done
syms x a b c
C = a * (x.^2) + (b * x) + c == 0;
x1 = subs(C,{a,b,c},{1,3,5});
solution = double(solve(x1,x));
Ameer Hamza
2020년 11월 16일
편집: Ameer Hamza
2020년 11월 16일
If a, b, and c are arrays
syms x a b c
av = [1 2 3];
bv = [4 5 6];
cv = [7 8 9];
C = a * (x.^2) + (b * x) + c == 0;
solution = cell(size(av));
for i = 1:numel(av)
x1 = subs(C,{a,b,c},{av(i),bv(i),cv(i)});
solution{i} = double(solve(x1,x));
end
solution is a cell array, where each cell contain solution for a combination of a, b, and c.
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