"functional approximation" is a correct and usable phrase in written English.
It can be used in various contexts, but it is commonly used in mathematics and computer science when describing a method of approximating a complex function with a simpler one. Example: "The algorithm used a functional approximation to estimate the value of the integral."
This control strategy employs the functional approximation technique to establish the unknown function for releasing the model-based requirement.
This control strategy employs the functional approximation technique to establish the unknown function for releasing the model based requirements of the sliding-mode control.
Staber, B; Guilleminot, J, Functional approximation and projection of stored energy functions in computational homogenization of hyperelastic materials: A probabilistic perspective, Computer Methods in Applied Mechanics and Engineering, vol 313 (2017), pp. 1-27 [abs1016/j.cma.2016.09.019] [abs].
One of those applications is the initialization of radial basis function (RBF) centers composing a neural network, designed to solve functional approximation problems.
Remsing, R. C., Klein, M. L. & Sun, J. Dependence of the structure and dynamics of liquid silicon on the choice of density functional approximation.
When the modeling errors are available, the indirect backstepping control is proposed, which can guarantee the functional approximation error will converge to a rather small neighborhood of the minimax functional approximation error.
Several density functional approximations that includes pure generalized gradient approximated (GGA) functional, meta-GGA, hybrid and range separated hybrid functionals have been used to evaluate the electrical band gap or transport gap of the studied polymers and compared with that obtained using Hubbard U corrected GGA functional (GGA+U).
Perdew, J. P. & Schmidt, K. Jacobs ladder of density functional approximations for the exchange correlation energy.
Li, C., Zheng, X., Cohen, A. J., Mori-Sánchez, P. & Yang, W. Local scaling correction for reducing delocalization error in density functional approximations.
Pernot, P., Civalleri, B., Presti, D. & Savin, A. Prediction uncertainty of density functional approximations for properties of crystals with cubic symmetry.
Surrogate models – simple functional approximations of complex models – can facilitate engineering analysis of complicated systems by greatly reducing computational expense.
