We derive an indefinite quadrature formula, based on a theorem of Ganelius,
for H-P functions, for p > 1, over the interval (-1, 1). The main factor i
n the error of our indefinite quadrature formula is O(e(-pi rootN/q)), with
2N nodes and 1/p + 1/q = 1 The convergence rate of our formula is better t
han that of the Stenger-type formulas by a factor of root2 in the constant
of the exponential. We conjecture that our formula has the best possible va
lue for that constant. The results of numerical examples show that our inde
finite quadrature formula is better than Haber's indefinite quadrature form
ula for H-P-Functions.