BJL(L, X, JL)
== MODIFIED SUBROUTINE FOR SPHERICAL BESSEL FUNCTIONS. ==!!
== CORRECTED THE SMALL BUGS IN PACKAGE CMBFAST&CAMB(for l=4,5, x~0.001-0.002)==!!
== CORRECTED THE SIGN OF J_L(X) FOR X<0 CASE ==!!
== WORKS FASTER AND MORE ACCURATE FOR LOW L, X<<L, AND L<<X cases ==!!
== zqhuang@astro.utoronto.ca ==!!