# KSPSTCGGetQuadratic

Gets the value of the quadratic function, evaluated at the new iterate:

### Synopsis

    #include "petscksp.h"
    PetscErrorCode PETSCKSP_DLLEXPORT KSPSTCGGetQuadratic(KSP ksp,PetscReal *quadratic)

q(s) = g^T * s + 0.5 * s^T * H * s

which satisfies the trust region constraint

|| s ||_M <= radius,

where

radius is the trust region radius, g is the gradient vector, and H is the Hessian matrix, M is the positive definite preconditioner matrix.

Collective on KSP

### Input Parameter

ksp -the iterative context

### Output Parameter

quadratic -the quadratic function evaluated at the new iterate

Level:advanced
Location: src/ksp/ksp/impls/cg/stcg/stcg.c
Index of all KSP routines
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