What does 'li' mean?

Hello all,

I have solved an equation in matlab using the following code:

syms x
ththa2 = (2*exp(5*x))/(3*exp(2*x)+1*exp(-2*x))
y = diff(ththa2)
eqn = y == 0
S = solve(eqn)

The answer is

S =

log(-(7^(1/2)*1i)/3)/2

log((7^(1/2)*1i)/3)/2

Would you please tell me what does this '1i' mean in the answer? What kind of a value is this?

Thank you,

Mohi

Answer 1

[KSSV]

1i stands for complex number. i.e. sqrt(-1).

c=2+3*i

c = 2.0000 + 3.0000i

c=2+3*1i

c = 2.0000 + 3.0000i

Answer 2

[Image Analyst]

It's i, the square root of -1, the imaginary constant.

Answer 3

[James Tursa]

1i is used to ensure it isn't confused with a variable named i that you might have in the workspace. I.e., 1i is always sqrt(-1), whereas just i might be sqrt(-1) or a variable that you created named i. It is common to see 1i used in MATLAB for sqrt(-1) because it is always unambiguous.