empty sym: 0-by-1 for Simultaneous equation

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Jacob Short
Jacob Short el 14 de En. de 2021
Respondida: Walter Roberson el 18 de En. de 2021
I'm trying to solve for these values but it keeps resulting in empty sym: 0-by-1. Any suggestions?
>> syms a b c d e x
>> equ1 = a + b == (0.83/12);
>> equ2 = c == (0.036/2);
>> equ3 = (0.048/16) + 2*0.21*x == 2*a + b + c + 2*d;
>> equ4 = 0.79*x == e;
>> equ5 = (a/(a + b + d + e)) == 0.109;
>> equ6 = (b/(b + a + d + e)) == 0.010;
>> equ7 = (d/(d + a + b + e)) == 0.071;
>> equ8 = (e/(e + a + b + d)) == 0.810;
>> sol = solve([equ1,equ2,equ3,equ4,equ5,equ6,equ7, equ8],[a,b,c,d,e,x]);

Respuestas (2)

Walter Roberson
Walter Roberson el 18 de En. de 2021
You are trying to solve 8 equations for 6 variables, but they are not consistent for all 8 equations.
syms a b c d e x
equ1 = a + b == (0.83/12);
equ2 = c == (0.036/2);
equ3 = (0.048/16) + 2*0.21*x == 2*a + b + c + 2*d;
equ4 = 0.79*x == e;
equ5 = (a/(a + b + d + e)) == 0.109;
equ6 = (b/(b + a + d + e)) == 0.010;
equ7 = (d/(d + a + b + e)) == 0.071;
equ8 = (e/(e + a + b + d)) == 0.810;
sol = solve([equ1,equ2,equ3,equ4,equ5,equ6],[a,b,c,d,e,x]);
subs(equ7, sol), vpa(ans)
ans = 
ans = 
subs(equ8, sol), vpa(ans)
ans = 
ans = 

Shashank Gupta
Shashank Gupta el 18 de En. de 2021
Hi Jacob,
If the solve function returns empty object then there is no solution exist for the given set of equations. I suggest you to check the feasibility of solution and equation first and then reform the equation and try.
Cheers.

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