Why does the variable 'ans' cannot be change when setting a domain? For example: I wanted to change the variable 'ans' to 'xofZ' but it keep saying it failed.

ans=solve(Iy1,x);

ans(ans==real(ans));

ans(ans>=0 & ans<=5)

e.g.

xofZ=solve(Iy1,x);

xofZ(ans==real(xofZ));

xofZ(xofZ>=0 & xofZ<=5)

Answer 1

[Voss]

If you want to modify the value of xofZ, e.g., by having it retain only the real solutions, you must assign to xofZ.

When the variable was ans, you didn't have to assign to ans because ans always contains the last unassigned result.

syms x

xofZ = solve(x.^3 + 2.*x.^2 + 2.*x == 0,x)

xofZ = 

% notice it says, ans = 0
xofZ(xofZ==real(xofZ))

ans = 

0

% but xofZ is still what it was:
xofZ

xofZ = 

% compared to this, which modifies xofZ
xofZ = xofZ(xofZ==real(xofZ))

xofZ = 

0

xofZ = xofZ(xofZ>=0 & xofZ<=5)

xofZ = 

0

[Qi Lun Ng]

Thank you very much!!!! It solved my issue

[Voss]

You're welcome!