The convergs function takes the continued fraction

and prints the successive convergents in the form n, nth convergent. The function convergs returns NULL.

listA is of the form $\[\mathrm{a1},\mathrm{a2},...\]$ and similarly listB is of the form $\[1,\mathrm{b2},\mathrm{b3},...\]$ where $\mathrm{aI}$ and $\mathrm{bI}$ correspond to the values in the displayed continued fraction.

If listB is of the form $\[1,1,1,...\]$ convergs may be omitted.

If a third argument n is present, convergs indicates the number of convergents to compute.