how do I write 2^-x in MatLab?

I need to run a algorithm where 2^(-x) is included.

Answer 1

[VBBV]

x=1:10;  % if you have x as vector of values 
2.^(-x)  % then use .^ element wise power

ans = 1×10

0.5000 0.2500 0.1250 0.0625 0.0312 0.0156 0.0078 0.0039 0.0020 0.0010

% 2nd option is straightforward
x = 2

x = 2

2^(-x)

ans = 0.2500

%To insert in a given fnction 
x = 1:0.1:10;
func = @(x) exp(x)+2.^(-x)+2*cos(x)

func = function_handle with value:
    @(x)exp(x)+2.^(-x)+2*cos(x)

plot(func(x))

Answer 2

[Fangjun Jiang]

x=1;
2^(-x)

ans = 0.5000

[John D'Errico]

The parens are not technically needed there, but they don't hurt anything.

x = 1;
2^-x

ans = 0.5000

And to be honest, I usually put a parens in something like that myself just to make it easier to read. Sometimes spare parens make things more clear, and sometimes they just create a confusing mess, creating a parenthetical balancing act.