.. _method-optpp_fd_newton-gradient_tolerance:

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gradient_tolerance
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Stopping critiera based on L2 norm of gradient


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**Specification**

- *Alias:* None

- *Arguments:* REAL

- *Default:* 1.e-4


**Description**


The ``gradient_tolerance`` control defines the
threshold value on the L2 norm of the objective function gradient
(for unconstrained minimum or no active constraints) or the
Lagrangian gradient (for constrained minimum) that
indicates convergence to a stationary point.
The ``gradient_tolerance`` control is currently defined
only for the OPT++ and ROL libraries.


