%!
/pi 3.1415927 def
% solving x = M + e sin (x) by iteration
% this is reasonable only if e is small
% stack: M e
/solve { 4 dict begin
/e exch def
/M exch def
% find n such that e^{n} < 10^{-7}, or n > -7 ln(10)/ln(e)
/n -7 10 log mul e log div cvi 1 add def
% M is the initial guess
M
% x on stack at start of loop
n {
% change x from radians to degrees
180 mul pi div sin e mul M add
} repeat
end } def