solve an equation system with matlab

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Alvaro Mª Zumalacarregui Delgado 2021-3-1

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https://ww2.mathworks.cn/matlabcentral/answers/759541-solve-an-equation-system-with-matlab

评论： Alvaro Mª Zumalacarregui Delgado 2021-3-1

I trying to solve a system but when I run matlab send me an error, this is the code

syms a b

xo = 7000;

yo = 8000;

x = 6600;

y = 6500;

t = 7;

eq1 = (b*xo-a*yo)/(exp(((b*xo-a*yo)*t)-((b*xo-a*yo)*(log(b*xo/yo)/(-(b*xo-a*yo)))))) == y;

eq2 = -(b*xo-a*yo)/(exp(((b*xo-a*yo)*t)-((b*xo-a*yo)*(log(-a*yo/xo)/(-(b*xo-a*yo)))))) == x;

solve([eq1 eq2], [a, b])

and the error

Warning: Unable to find explicit solution. For options, see help.

> In sym/solve (line 317)

In sistema (line 16)

ans =

struct with fields:

a: [0×1 sym]

b: [0×1 sym]

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Star Strider 2021-3-1

在 MATLAB Online 中打开

The two functions do not intersect, so they have no values of either ‘a’ or ‘b’ in common:

syms a b
xo = 7000;
yo = 8000;
x  = 6600;
y  = 6500;
t  = 7;
 
eq1 = (b*xo-a*yo)/(exp(((b*xo-a*yo)*t)-((b*xo-a*yo)*(log(b*xo/yo)/(-(b*xo-a*yo)))))) == y;
 
eq2 = -(b*xo-a*yo)/(exp(((b*xo-a*yo)*t)-((b*xo-a*yo)*(log(-a*yo/xo)/(-(b*xo-a*yo))))))  == x;
eq1 = simplify(lhs(eq1)-rhs(eq1), 'Steps',500);
eq2 = simplify(lhs(eq2)-rhs(eq2), 'Steps',500);
figure
fsurf(eq1, [-1 1  -1 1]*1E+8)
hold on
fsurf(eq2, [-1 1  -1 1]*1E+8)
hold off