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@@ -9,6 +9,7 @@ def prime(n):
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return False
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return True
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+# Set of helper functions along each diagonal
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def upright(d):
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return 4*d**2-10*d+7
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def upleft(d):
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@@ -18,32 +19,27 @@ def downleft(d):
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def downright(d):
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return 4*d**2-4*d+1
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-def percentPrimeSpiral(sideLen):
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+# Starting values for while loop
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+primeRatio = 1.0
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+sideLen = 3
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+numPrimes = 0
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+
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+while primeRatio > 0.10:
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diagonalLen = (sideLen+1)/2
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totalDiagonals = (diagonalLen-1)*4 + 1
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- numPrimes = 0
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- for i in range(1,diagonalLen+1):
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- if prime(upright(i)):
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- numPrimes += 1
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- if prime(upleft(i)):
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- numPrimes += 1
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- if prime(downright(i)):
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- numPrimes += 1
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- if prime(downleft(i)):
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- numPrimes += 1
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- return numPrimes / float(totalDiagonals)
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-
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-def main():
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- primeRatio = .99
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- sideLen = 1001
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-
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- while primeRatio > 0.12:
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- primeRatio = percentPrimeSpiral(sideLen)
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- sideLen += 10
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- print primeRatio
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-
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- print sideLen
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- print primeRatio
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-
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-main()
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+ if prime(upright(diagonalLen)):
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+ numPrimes += 1
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+ if prime(upleft(diagonalLen)):
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+ numPrimes += 1
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+ if prime(downright(diagonalLen)):
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+ numPrimes += 1
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+ if prime(downleft(diagonalLen)):
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+ numPrimes += 1
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+
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+ primeRatio = numPrimes / float(totalDiagonals)
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+ sideLen += 2
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+
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+# Adjust sidelength by 2
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+print sideLen - 2
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+print primeRatio
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