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Parabolic cylinder functions - Read

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III. SOLUTIONS OF EQUATION 2<br />

A. Standard solution<br />

The standard solution W (a, x) of Eq. (2) is<br />

where<br />

3<br />

−<br />

W (a, ±x) = 2 4 (<br />

G1<br />

y1 ∓<br />

G3<br />

4<br />

<br />

2G3<br />

y2), (19)<br />

G1 = |Γ(ia + 1<br />

4 )|, G3 = |Γ(ia + 3<br />

)|,<br />

4<br />

(20)<br />

y1 = 1 + a x2<br />

2! + (a2 − 1<br />

2 )x4<br />

4! + (a3 − 7a<br />

2 )x6<br />

6! + (a4 − 11a 2 + 15<br />

4 )x8 + . . . ,<br />

8!<br />

(21)<br />

y2 = x + a x3<br />

3! + (a2 − 3<br />

2 )x5<br />

5! + (a3 − 13a<br />

2 )x7<br />

7! + (a4 − 17a 2 + 63<br />

4 )x9 + . . . ,<br />

9!<br />

(22)<br />

in which the coefficients An of xn<br />

n!<br />

G1<br />

obey the recurrence relation<br />

An+2 = aAn − 1<br />

4 n(n − 1)An−2. (23)<br />

Relations for gamma function of complex argument are given in Appendix A. At x = 0,<br />

<br />

3<br />

− G1<br />

W (a, 0) = 2 4<br />

G3<br />

W ′ 1<br />

−<br />

(a, 0) = −2 4<br />

G3<br />

B. Relations at large values of argument x<br />

,<br />

. (24)<br />

G1<br />

At large values of the argument x, when x ≫ |a|, there are relations<br />

<br />

2k<br />

W (a, x) =<br />

x [s1(a, x) cos γ − s2(a, x) sin γ],<br />

<br />

2<br />

W (a, −x) =<br />

kx [s1(a, x) sin γ + s2(a, x) cos γ], (25)<br />

where<br />

with<br />

k = √ 1 + e 2πa − e πa , k −1 = √ 1 + e 2πa + e πa , (26)<br />

γ = x2<br />

4<br />

− a ln x + π<br />

4<br />

φ<br />

+ , (27)<br />

2<br />

φ = arg Γ(ia + 1<br />

), (28)<br />

2

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