Evaluate Symbolic Expressions Using subs
When you assign a value to a symbolic variable, expressions containing the variable are
not automatically evaluated. Instead, evaluate expressions by using
subs
.
Define the expression y = x^2
.
syms x y = x^2;
Assign 2
to x
. The value of y
is
still x^2
instead of 4
.
x = 2; y
y = x^2
If you change the value of x
again, the value of y
stays x^2
. Instead, evaluate y
with the new value of
x
by using subs
.
subs(y)
ans = 4
The evaluated result is 4
. However, y
has not
changed. Change the value of y
by assigning the result to
y
.
y = subs(y)
y = 4
Show that y
is independent of x
after this
assignment.
x = 5; subs(y)
ans = 4