Solving multiple algebraic equation

I am trying to solve 3 unknown using the following code. Am I doing this right ?

>> clear all

>> syms x y z

>> eqns=[x==(0.134+0.01*sin(z))/0.464189, 0.134*z==0.01*cos(z), y==z/x];

>> S=solve(eqns,[x y z])

Warning: Cannot solve symbolically. Returning a numeric approximation instead.

> In solve (line 303)

S =

struct with fields:

x: [1×1 sym]

y: [1×1 sym]

z: [1×1 sym]

>> S.x

ans =

0.29027727131273067299254520400093

>> S.y

ans =

0.25637661763413173595586063384135

>> S.z

ans =

0.074420304995223068940034251420538

[Walter Roberson]

Yes, provided you want to restrict to reals.

However in this situation, you only need to solve the second equation. The z you get from that defines what x must be, and then the third equation defines y in terms of the x and z.

[Aqmar Azlan]

Got it ! Thank you for your help

Answer 1

[Mahesh Taparia]

Hi,

Your solution is correct.

Use ‘S=vpasolve(eqns,[x y z]) ‘ instead of using ‘solve’ command, to avoid warning. Your solution is an approximate to your exact solution. By default, ‘vpa’ uses 32 significant decimal digits of precision, you can change the precision using digits command. For further information, you can refer the following link:

https://www.mathworks.com/help/symbolic/increase-precision-of-numeric-calculations.html