// InvX = frcpa(x)
// r = InvX*x - 1
// P(r) = r*((r*A3 - A2) + r^4*((A4 + r*A5) + r^2*(A6 + r*A7)),
-// all coefficients are calcutated in quad and rounded to double
+// all coefficients are calculated in quad and rounded to double
// precision. A7,A6,A5,A4 are stored in memory whereas A3 and A2
// created with setf.
//