I'm searching how Pd does to calculate the value of a table when we use the function sinesum.

for example :
[array1 sinesum 64 1(
will give this number in a table :

0. -0.0980171
1. 0
2. 0.0980171
3. 0.19509
4. 0.290284
5. 0.382683
6. 0.471396
7. 0.55557

comparing this value to other obtained with a table of 128, and with the function sin^-1, I found the value correspond to this formula :
sin(L / 651.898912 * [n-1] )
where L is the size of the table, and n the index.

can someone explain this number 651.898912 ? or know the exact formula ? and for many sinusoid ?
thanks

The function is sin((n-1) * 2pi / L).

thank you so much ,
do you have it for many partials ?

sum(A_i * sin(i * (n-1) * 2pi / L), for i=1 to M)

where i is the partial number, A_i is the amplitude of partial i, and M is the number of partials.

thanks