thanks a lot, I just change the style of writing.
But how can I express some constrains like:
x>=1 or x<=-2
I couldn’t find the symbol to express “or” and I couldn’t use expressions like “abs(x)>= constant”
You can handle x>=1 or x<=-2
by brute force, by solving separate problems for x>=1 and for x <= 2 (x is presumably a vector with dimension > 1, or else in this example, the “or” is always satisfied), and taking as your solution, the best solution of the separate problems. If you have several instances of “or”, this approach would result in a combinatorial blow up. I think you could alternatively use the mixed integer capability of CVX.
As for abs(x) >= constant, that is (very) non-convex (unless the constant is zero). So of course CVX won’t let you use that.