"variation of constants" is a correct and usable phrase in written English.
You can use it to refer to a situation where certain parameters or constants are subject to change or variation. For example, you could say "The theory of relativity requires a variation of constants in order to be consistent with observations."
A key tool is a new formula of variation of constants that works for such quadratic equations.
The effect of the variation of constants which define analytically the fiber orientation is also investigated by several parametric studies.
These numerical integrators are based on the variation of constants solution and solving the linear system exactly.
A computational procedure is presented for approximating elliptic halo orbits about the collinear equilibrium points based on the variation of constants in the sense of the second-order approximation.
by using the variation of constants formula.
The variation of constants formula yields (3.6).
Next, combining the general variation-of-constants formula with the state-dependent switching rule, new approaches are presented to design the feedback controller and the switching rules.
The integrators are a blend of the existing Filon-type methods and asymptotic methods based on the variation-of-constants formula.
First, by introducing the general variation-of-constants formula of neutral systems with perturbation, the BIBO stability property of general linear switched neutral systems with perturbation is established.
To this end, under the assumption of periodic boundary conditions, we begin with the formulation of the nonlinear Klein Gordon equation as an abstract second-order ordinary differential equation (ODE) and its operator-variation-of-constants formula.
We then introduce an operator-variation-of-constants formula which is essential for the derivation of our arbitrarily high-order Lagrange collocation-type time-stepping schemes for the nonlinear abstract ODE.
