Is there a mistake in my code?
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Hello everyone,
I need to plot a graph and after many trials and errors I came up with this code:
syms A B
D1= 12*A + 19.7891*B == 78.8820;
D2= 19.7891*A + 449*B == 44700;
sol=solve([D1,D2], [A,B]);
A=sol.A % A= -169.9537
B=sol.B % B= 107.0451
a=exp(A)
x=2.5:0.1:10
y=a*(x.^B);
plot(x,y)
However the graph I end up with is nothing like the graph I need. This is the graph I get:
And this is the graph I need:
I double-checked the values of all the variables and they are all correct, so I'm thinking I must have made a mistake with the syntax or the commands themselves, but I can't figure it out. I would appreciate any help you can give me.
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Star Strider
2022-1-9
I might be better to estimate the parameters directly —
x = [2.5 6 9]; % Excerpt From Plot
y = [1500 600 400]; % Excerpt From Plot
pwrfcn = @(b,x) b(1) .* x.^b(2); % Objective Function
[B,fv] = fminsearch(@(b)norm(y - pwrfcn(b,x)), rand(2,1))
xv = 2.5:0.1:10;
figure
plot(x, y, 'pk')
hold on
plot(xv, pwrfcn(B, xv), '-b')
hold off
grid
.
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