In Chapter 2, Section 5 of Chavel's book, regarding the Neumann eigenvalues of the Laplacian in space forms, how did Chavel determine that $T'_{l,j}$ has ($j-1$) zeros? I have consulted books on the Sturm–Liouville theory and could only confirm that $T_{l,j}$ has ($j-1$) zeros. How can one obtain the distribution of zeros of the derivative of the eigenfunctions?
T'
orT^\prime
, not $T^{'}$T^{'}
. Notice that the prime in the latter is too high and too small. I have edited accordingly. $\endgroup$