Solving equation with symbolic vector variable
35 views (last 30 days)
Show older comments
Delia Bosshart
on 19 Apr 2021
Commented: Delia Bosshart
on 19 Apr 2021
I want to solve an equation, a b c d are known vectors and x is the symbolic vector variable I want to solve for.
In the output I get only the 'names' of the elements (x1, x2, ...) How do I get the values of x1,x2 ? Any help is much appreciated.
SIMPLIFIED PROBLEM:
input:
a = [1 2 3 4];
x = sym('x', [1 4]);
eqn = a + 4.*x == x;
vpasolve(eqn, x)
Output:
ans =
struct with fields:
x1: [1×1 sym]
x2: [1×1 sym]
x3: [1×1 sym]
x4: [1×1 sym]
REAL PROBLEM:
Input:
a = data{23:29,6}; %q_inc
b = data{23:29,16}; %q_losses
c = data{23:29,15}; %rho_char
d = data{23:29,14}; %betta_char
x = sym('x', [1 9]);
eqn = (a - b + 6.96.*x + (6-(31.*c)./1000).*x./60*1000 + 31.*c./1000.*d./60*1000)*0.0081 - 0.1824 - x == 0;
vpasolve(eqn,x)
Output:
ans =
struct with fields:
x1: [1×1 sym]
x2: [1×1 sym]
x3: [1×1 sym]
x4: [1×1 sym]
...
0 Comments
Accepted Answer
Stephan
on 19 Apr 2021
use the dot-notation
a = [1 2 3 4];
x = sym('x', [1 4]);
eqn = a + 4.*x == x;
sol_x = vpasolve(eqn, x)
sol_x.x1
sol_x.x2
sol_x.x3
sol_x.x4
2 Comments
Walter Roberson
on 19 Apr 2021
a = [1 2 3 4];
x = sym('x', [1 4]);
eqn = a + 4.*x == x;
temp = struct2cell(vpasolve(eqn, x));
vertcat(temp{:})
More Answers (0)
See Also
Categories
Find more on Equation Solving in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!