Apply suggestions from code review

Co-authored-by: Dominique <dominique.orban@gmail.com>

Author: geoffroyleconte

src/qp_rand_model.jl

@@ -6,9 +6,9 @@ using .QuadraticModels
 
 Return an instance of a `QuadraticModel` representing
 
-   ½ xᵀHx + cᵀx   s.t.  l ≤ x ≤ u,
+   min cᵀx + ½ xᵀHx   s.t.  l ≤ x ≤ u,
 
-with H = A + A' or H = A * A' + I (see the `convex` keyword argument) where A is a random square matrix with density `dens`, `l = -e -tₗ` and `u = e + tᵤ` where `tₗ` and `tᵤ` are sampled from a uniform distribution between 0 and 1.    
+with H = A + A' or H = A * A' (see the `convex` keyword argument) where A is a random square matrix with density `dens`, `l = -e - tₗ` and `u = e + tᵤ` where `e` is the vector of ones, and `tₗ` and `tᵤ` are sampled from a uniform distribution between 0 and 1.    
 
 ## Arguments
 
@@ -17,15 +17,15 @@ with H = A + A' or H = A * A' + I (see the `convex` keyword argument) where A is
 ## Keyword arguments
 
 * `dens :: Real`: density of `A`` used to generate the quadratic model (default: `1.0e-4`).
-* `convex :: Bool`: true to generate a convex `H` (default: `false`).
+* `convex :: Bool`: true to generate positive definite `H` (default: `false`).
 
 ## Return Value
 
 An instance of a `QuadraticModel`.
 """
 function qp_rand_model(n::Int; dens::R = 1.0e-4, convex::Bool = false) where {R <: Real}
   A = sprandn(R, n, n, dens)
-  H = convex ? (A * A') : (A + A') #+ I
+  H = convex ? (A * A') : (A + A')
   c = randn(R, n)
   l = -one(R) .- rand(R, n)
   u = one(R) .+ rand(R, n)