How can i set input command for undefined variable?

I have a input.

 x_ang = [0 0 15 15 30, fliplr([0 0 15 15 30])];% [X,NN] = RunLength(x_ang); 

 it = 10; x=4;y=10;

if a comment on x_ang,

 %x_ang = [0 0 15 15 30, fliplr([0 0 15 15 30])];% [X,NN] = RunLength(x_ang);

and if "x_ang" is not available, then i want to input automatically x_ang, then how can i make condition for this?

Answer 1

[Walter Roberson]

if ~exist('x_ang', 'var')
  x_ang = input('Enter x_ang values');
end