Perturbation theory and approximation - help!
135885
Find a two-term expansion for the root of 1+\sqrt(x^2+\epsilon)=e^x.
21805
Scattering, Perturbation and asymptotic states in LSZ reduction formula
7945
Approximate $|x|$ with a smooth function
17414
Lagrangian of an effective potential
148914
Total Variation and indefinite integrals
29952
Time-ordering vs normal-ordering and the two-point function/propagator
157917
Calculate the leading order asymptotic behaviour (with two maxima)
32209
Labeling solutions of an Eigenvalue equation involving Bessel functions
1331
Approximation of the Sine function near $0$
133844
Numerical solution to Schrödinger equation - eigenvalues
129170
Deriving the expectation of $[\hat X,\hat H]$
126425
Consistent, complete, and generalized description of the quantum harmonic oscillator
44747
Finding the effective Hamiltonian in a certain subspace
150981
Why doesn't using the approximation $\sin x\approx x$ near $0$ work for computing this limit?
29983
How to compute the pade approximation?
48246
Approximation of Riemann integrable function with a continuous function
153300
Uniform approximation by even polynomial