Created
March 14, 2012 06:13
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def extr(a,x) | |
q,r,s,t = a | |
((q.to_r * x + r.to_r) / (s.to_r * x + t.to_r)) | |
end | |
def comp(a,b) | |
q,r,s,t = a | |
u,v,w,x = b | |
[q*u+r*w, q*v+r*x, s*u+t*w, s*v+t*x] | |
end | |
def stream(nxt, safe, prod, cons, init, input) | |
Enumerator.new do |yielder| | |
memo = init | |
next_memo = nxt.call(memo) | |
input.each do |x| | |
while safe.call(memo, next_memo) | |
yielder << next_memo | |
memo = prod.call(memo, next_memo) | |
next_memo = nxt.call(memo) | |
end | |
memo = cons.call(memo,x) | |
next_memo = nxt.call(memo) | |
end | |
end | |
end | |
def process(nxt, prod, cons, init, input) | |
Enumerator.new do |yielder| | |
memo = init | |
input.each do |x| | |
v = cons.call(memo,x) | |
y = nxt.call(v) | |
yielder << y | |
memo = prod.call(v,y) | |
end | |
end | |
end | |
pi = stream( | |
->(z){extr(z,3).to_i}, #nxt | |
->(z,n){n == extr(z,4).to_i}, #safe | |
->(z,n){comp([10,-10*n,0,1], z)}, #prod | |
->(z,z1){comp(z,z1)}, #cons | |
[1,0,0,1], #init | |
Enumerator.new{|y| i=0; loop{i+=1; y << [i, 4*i+2, 0, 2*i+1]}} # input | |
) | |
piL = stream( | |
->(a) do #nxt | |
z,i = a | |
q,r,s,t = z | |
x = 2*i-1 | |
((q*x+r) / (s*x+t)).to_i | |
end, | |
->(a,n) do #safe | |
z,i = a | |
q,r,s,t = z | |
x = 5*i-2 | |
n == ((q*x+2*r) / (s*x+2*t)).to_i | |
end, | |
->(a,n) do #prod | |
z,i = a | |
[comp([10,-10*n,0,1],z), i] | |
end, | |
->(a,z1) do #cons | |
z,i = a | |
[comp(z,z1), i+1] | |
end, | |
[[0,4,1,0],1], #init | |
Enumerator.new{|y| k=0; loop{k+=1; y << [2*k-1, k*k, 1, 0]}} #input | |
) | |
# This one doesn't return correct results. But as far as I can see, my port is faithful. Did I miss something? | |
piG = stream( | |
->(a) do #nxt | |
z,i = a | |
q,r,s,t = z | |
x = 27*i+15 | |
((q*x+5*r) / (s*x+5*t)).to_i | |
end, | |
->(a,n) do #safe | |
z,i = a | |
q,r,s,t = z | |
x = 675*i-216 | |
n == ((q*x+125*r) / (s*x+125*t)).to_i | |
end, | |
->(a,n) do #prod | |
z,i = a | |
[comp([10,-10*n,0,1],z),i] | |
end, | |
->(a,z1) do #cons | |
z,i = a | |
[comp(z,z1),i+1] | |
end, | |
[[1,0,0,1],1], #init | |
Enumerator.new{|y| k=0; loop{k+=1; j = 3*(3*k+1)*(3*k+2); y << [k*(2*k-1), j*(5*k-2), 0, j]}} #input | |
) | |
piG2 = process( | |
->(a) do #nxt | |
z,i = a | |
q,r,s,t = z | |
x = 27*i+15 | |
((q*x+5*r) / (s*x+5*t)).to_i | |
end, | |
->(a,n) do #prod | |
z,i = a | |
[comp([10,-10*n,0,1],z),i] | |
end, | |
->(a,z1) do #cons | |
z,i = a | |
[comp(z,z1),i+1] | |
end, | |
[[1,0,0,1],1], #init | |
Enumerator.new{|y| k=0; loop{k+=1; j = 3*(3*k+1)*(3*k+2); y << [k*(2*k-1), j*(5*k-2), 0, j]}} #input | |
) | |
pi.take(100) | |
piL.take(100) | |
#piG.take(100) | |
piG2.take(100) | |
piG2.each{|d| $stdout.print d; $stdout.flush} |
I ported the code in the link in the description.
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