FIG. 3: R$_{p,q}$ ( n, n/ 2 (1 + µ ) $_{, x}$√$_{n}$$_{) (blue curves) versus}$$_{x}$$_{at}$ µ = 1 / 3 and z = − 9 so that q = 1 − 9 /n and p = 1 − 0 . 153208 /n for n = 2 $^{6}$, 2$^{8}$, 2$^{10}$, 2$^{12}$, 214 and 2 $^{16}$. The red curve is the asymptote e − 0 . 103551 x $^{2}$. Having moved in the z -direction from z$_{0}$ to z$_{1}$ we now compute the point y$_{2}$ so that ( y$_{2}$, z$_{1}$ ) stays on the isocurve with R$_{p,q}$ ( n, n/ 2 , 1) = 1. A small change in z requires only a small change in y to preserve this property. With w$_{0}$ = W ( z$_{0}$ e z$_{0}$/ $^{2}$/ 2 ) we have the series expansion giving an approximation for small x . We want to set and thus we have 24 W ( ( z$_{0}$ + x ) exp (( z$_{0}$ + x ) / 2) 2 ) = w$_{0}$ + x w$_{0}$ ( z$_{0}$ + 2) 2 z$_{0}$ ( w$_{0}$ + 1) + · · · (80) x = s √$_{1 +}$$_{t}$ 2 √$_{n}$ (81) y$_{2}$ = y$_{0}$ + s w$_{0}$ ( z$_{0}$ + 2) z$_{0}$ ( w$_{0}$ $_{+ 1)}$√$_{1 +}$$_{t}$ 2 √$_{n}$ (82) $^{GLYPH<Minus>}$6 $^{GLYPH<Minus>}$4 $^{GLYPH<Minus>}$2 2 4 6 x 0.2 0.4 0.6 0.8 1.0 R