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Contents
describe Integer, "#semiperfect?" do
# A005835
@seq = [6,12,18,20,24,28,30,36,40,42,48,54,56,60,66,72,
78,80,84,88,90,96,100,102,104,108,112,114,120,126,
132,138,140,144,150,156,160,162,168,174,176,180,
186,192,196,198,200,204,208,210,216,220,222,224,
228,234,240,246,252,258,260,264].to_seq
@seq.each do |n|
it "returns true for semi-perfect number #{n}" do
n.should be_semiperfect
end
it "returns false for negative number #{-n}" do
(-n).should_not be_semiperfect
end
end
@seq.invert.sample(10).each do |n|
it "returns false for non-semi-perfect number #{n}" do
n.should_not be_semiperfect
end
end
# Guy, R. K.
# "Almost Perfect, Quasi-Perfect, Pseudoperfect, Harmonic, Weird,
# Multiperfect and Hyperperfect Numbers."
# §B2 in Unsolved Problems in Number Theory, 2nd ed. New York:
# Springer-Verlag, pp. 45-53, 1994
it "returns true for 2**m * p (where m >= 1 && p.prime? && (p < 2**(m+1) && p > 2**m)" do
[[4, 17], [4, 19], [4, 23], [4, 29], [4, 31],
[5, 37], [5, 41], [5, 43], [5, 47], [5, 53], [5, 59], [5, 61],
[6, 67], [6, 71], [6, 73], [6, 79], [6, 83], [6, 89], [6, 97],
[6, 101],[6, 103],[6, 107],[6, 109],[6, 113],[6, 127]].shuffle.first(10).each do |m,p|
(2**m * p).should be_semiperfect
end
end
it "handles large input quickly and without raising a RangeError" do
require 'timeout'
lambda do
Timeout.timeout(5) { 19305.semiperfect? }
end.should_not raise_error
end
end
Version data entries
16 entries across 16 versions & 1 rubygems