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- #!/usr/bin/ruby
- #
- ## https://rosettacode.org/wiki/Imaginary_base_numbers
- #
- func base (Number num, Number radix { _ ~~ (-36 .. -2) }, precision = -15) -> String {
- num || return '0'
- var place = 0
- var result = ''
- var value = num
- var upper_bound = 1/(-radix + 1)
- var lower_bound = radix*upper_bound
- while (!(lower_bound <= value) || !(value < upper_bound)) {
- value = num/(radix**++place)
- }
- while ((value || (place > 0)) && (place > precision)) {
- var digit = (radix*value - lower_bound -> int)
- value = (radix*value - digit)
- result += '.' if (!place && !result.contains('.'))
- result += ((digit == -radix) ? (digit-1 -> base(-radix) + '0') : digit.base(-radix))
- place--
- }
- return result
- }
- func base (Number num, Number radix { .re == 0 }, precision = -8) -> String {
- (radix.im.abs ~~ 2..6) || die "Base #{radix} out of range"
- var (re, im) = (num.re, num.im)
- var (re_wh, re_fr='') = base(re, -radix.im**2, precision).split('.')...
- var (im_wh, im_fr='') = base(im/radix.im, -radix.im**2, precision).split('.')...
- func zip (String a, String b) {
- var l = ('0' * abs(a.len - b.len))
- chars(a+l) ~Z chars(b+l) -> flat.join.sub(/0+\z/, '') || '0'
- }
- var whole = zip(re_wh.flip, im_wh.flip).flip
- var fraction = zip(im_fr, re_fr)
- fraction == '0' ? whole : "#{whole}.#{fraction}"
- }
- func parse_base (String str, Number radix { .re == 0 }) -> Number {
- if (str.char(0) == '-') {
- return (-1 * parse_base(str.substr(1), radix))
- }
- var (whole, frac='') = str.split('.')...
- var fraction = frac.chars.map_kv {|k,v|
- Number(v, radix.im**2) * radix**-(k+1)
- }.sum
- fraction += whole.flip.chars.map_kv {|k,v|
- Number(v, radix.im**2) * radix**k
- }.sum
- return fraction
- }
- var tests = [0, 2i, 1, 2i, 5, 2i, -13, 2i, 9i, 2i, -3i, 2i, 7.75-7.5i, 2i, .25, 2i, # base 2i tests
- 5+5i, 2i, 5+5i, 3i, 5+5i, 4i, 5+5i, 5i, 5+5i, 6i, # same value, positive imaginary bases
- 5+5i, -2i, 5+5i, -3i, 5+5i, -4i, 5+5i, -5i, 5+5i, -6i, # same value, negative imaginary bases
- 227.65625+10.859375i, 4i] # larger test value
- tests.each_slice(2, {|v,r|
- var ibase = base(v, r)
- printf("base(%20s, %2si) = %-10s : parse_base(%12s, %2si) = %s\n",
- v, r.im, ibase, "'#{ibase}'", r.im, parse_base(ibase, r).round(-8))
- })
- assert_eq(base(tests[-2], tests[-1]), "10234.5678")
- assert_eq(parse_base("10234.5678", tests[-1]).round(-8), 227.65625+10.859375i)
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