# check

check is used to examine satisfaction of constraints.

### Syntax

```
[primalfeas,dualfeas] = check(F);
```

### Examples

After solving a problem, we can easily check how well the constraints are satisfied.

```
x = sdpvar(2,1);
F = [-1 <= x <= 1];
optimize(F,sum(x));
check(F)
```

The constraint residuals are defined as smallest eigenvalue, smallest element, negated largest absolute-value element and largest distance to an integer for semidefinite inequality, element-wise inequality, equality and integrality constraints respectively. Hence, a solution is feasible if all residuals related to inequalities are non-negative.

Sometimes it is convenient to have the numerical values of the primal and dual constraint violations

```
[primalfeas,dualfeas] = check(F);
```

### Comments

Almost all solvers are prone to return slightly infeasible solution, hence it is up to the user to judge if a given solution actually is practically feasible or infeasible.

Also note that check only computes residuals. It does not judge if these indicate infeasibility. Once again, **it is up to the user to interpret the numbers**.

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