I got "The expression to the left of the equals sign is not a valid target for an assignment."

3 views (last 30 days)
Hello, when I run my code, i get error.
I can not see my fault. There is something wrong about i^2=-1 But I must use that expression.
Thank you.
clc
clear all
close all
fprintf('%10s %10s %10s %10s\n','k','real(xk)','imag(xk)','|f(xk)|')
k = 0 ;
i^2 = -1 ;
x = -2-2i;
f = @(x) x^3 - x - 3 ;
while abs(f(x)) > 10^(-5)
f = @(x) x^3 - x - 3 ;
diff = @(x) 3*(x^2) - 1 ;
xreal = real(x);
ximag = imag(x);
xnew = x - (f(x) / diff(x));
fprintf('%10.4f %10.4f %10.4f %10.4f\n',k,xreal,ximag,f(x))
x = xnew;
k = k +1;
end

Accepted Answer

Steven Lord
Steven Lord on 16 Apr 2019
Just eliminate that line from your code. The way you've defined x on the next line will make it complex since i is already defined to be the imaginary unit.

More Answers (1)

Kelly Kearney
Kelly Kearney on 16 Apr 2019
As others have pointed out, i is already assigned the value you want by default.
But assuming it weren't, the proper way to assign the value would be:
i = sqrt(-1);
The error is basically telling you that Matlab won't implictly do any algebra for you... you can only assign a value to a variable, not to a function or equation like you attempted to do.

Categories

Find more on Startup and Shutdown 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!