The phrase "a closed form approximation" is correct and usable in written English.
It can be used in mathematical or scientific contexts when discussing a simplified expression that approximates a more complex function or solution.
Example: "In our analysis, we derived a closed form approximation for the integral, which significantly simplifies the calculations."
Alternatives: "a simplified expression" or "an analytical approximation".
Equation 21 is a closed form approximation, so it allows us to directly find an approximate CDF of the PAPR without complex operations.
A closed form approximation is found which is valid in a very broad materials parameter window.
A closed form approximation for the peak impact load is then used to predict the delamination threshold velocity.
A response surface method in conjunction with design of experiments is used to develop a closed form approximation of the fatigue damage accumulation with respect to the input random variables.
We present a closed form approximation to the power in terms of the genetic model, pooling measurement error model, and the study parameters (e.g., number of pools, number of replicates per pool, sample size) and we perform a systematic study of the design parameters to identify which have the greatest effect on power to detect association for DNA pooling studies.
This approach also aids in deriving the closed form approximation of network survivability based on network characteristic functionalities and node behaviour distribution.
However, current knowledge of the closed form approximation covers only sample size and power calculation in general linear multivariate models with a single, continuous, normally distributed predictor variable [ 13].
Although closed form approximations (Liu et al., 2006; Sykacek et al., 2007) have computational advantages, we prefer here an unbiased approximation and follow (Bae and Mallick, 2004; Gottardo et al., 2006; Huang et al., 2002; Lewin et al., 2007; Shahbaba and Neal, 2006; Tadesse et al., 2003) who, among many others, have previously used Markov chain Monte Carlo (MCMC) in a bioinformatics context.
A closed form solution for the approximation of a linear-phase FIR (finite impulse response) filter with equiripple magnitude responsein the passband and stopband was not known.
Since it is normally difficult to obtain a closed form solution, finite element approximations of optimal control problems governed by partial differential equations have been extensively studied in the literature.
A closed form formula on the error of approximation is derived to demonstrate the accuracy of the proposed discretization model of fractional derivatives.
