Three word location: Difference between revisions

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=={{header|Phix}}==

<lang Phix>requires("0.8.2") -- (new || && << and >> operators, pre-0.8.2 code left in as comments)

--

-- demo\rosetta\Three_word_location.exw

function toWord(integer w)

-- ====================================

return sprintf("W%05d", w)

--

end function

with javascript_semantics

function fromWord(string ws)

function toWord(integer w)

sequence r = scanf(ws,"W%05d")

return sprintf("W%05d", w)

integer res = r[1][1]

end function

return res

end function

function fromWord(string ws)

sequence r = scanf(ws,"W%05d")

printf(1,"Starting figures:\n")

integer res = r[1][1]

atom lat = 28.3852,

return res

lon = -81.5638

end function

printf(1," latitude = %0.4f, longitude = %0.4f\n", {lat, lon})

printf(1,"Starting figures:\n")

-- convert lat and lon to positive integers

atom lat = 28.3852,

integer ilat := floor((lat+90)*10000),

lon = -81.5638

ilon := floor((lon+180)*10000)

printf(1," latitude = %0.4f, longitude = %0.4f\n", {lat, lon})

-- build 43 bit BigInt comprising 21 bits (lat) and 22 bits (lon)

-- convert lat and lon to positive integers

-- (Std phix atoms have 53/64 bits of precision on 32/64 bit, both plenty)

integer ilat := floor((lat+90)*10000),

--atom latlon := ilat*power(2,22) + ilon -- (pre-0.8.2)

ilon := floor((lon+180)*10000)

atom latlon := (ilat << 22) + ilon

-- build 43 bit BigInt comprising 21 bits (lat) and 22 bits (lon)

-- isolate relevant bits

-- (std phix atoms have 53/64 bits of precision on 32/64 bit, both plenty)

--integer w1 = and_bits(floor(latlon/power(2,28)),0x7fff), --("")

atom latlon := (ilat << 22) + ilon

-- w2 = and_bits(floor(latlon/power(2,14)),0x3fff),

-- w3 = and_bits(latlon,0x3fff)

-- isolate relevant bits

integer w1 = (latlon >> 28) && 0x7fff,

integer w1 = (latlon >> 28) && 0x7fff,

w2 = (latlon >> 14) && 0x3fff,

w2 = (latlon >> 14) && 0x3fff,

w3 = latlon && 0x3fff

w3 = latlon && 0x3fff

-- convert to word format

-- convert to word format

string w1s = toWord(w1),

string w1s = toWord(w1),

w2s = toWord(w2),

w2s = toWord(w2),

w3s = toWord(w3)

w3s = toWord(w3)

-- and print the results

-- and print the results

printf(1,"\nThree word location is:\n")

printf(1,"\nThree word location is:\n")

printf(1," %s %s %s\n", {w1s, w2s, w3s})

printf(1," %s %s %s\n", {w1s, w2s, w3s})

-- now reverse the procedure

-- now reverse the procedure

w1 = fromWord(w1s)

w1 = fromWord(w1s)

w2 = fromWord(w2s)

w2 = fromWord(w2s)

w3 = fromWord(w3s)

w3 = fromWord(w3s)

-- NB: or_bits (likewise ||), being expressly 32-bit, is NOT appropriate here...

-- NB: or_bits (likewise ||), being expressly 32-bit, is NOT appropriate here...

--latlon = w1*power(2,28) + w2*power(2,14) + w3 -- (pre-0.8.2)

latlon = (w1 << 28) + (w2 << 14) + w3

--ilat = floor(latlon/power(2,22))

ilat = latlon >> 22

--ilon = and_bits(latlon,0x3fffff)

ilon = latlon && 0x3fffff

latlon = (w1 << 28) + (w2 << 14) + w3

lat = ilat/10000 - 90

ilat = latlon >> 22

lon = ilon/10000 - 180

ilon = latlon && 0x3fffff

lat = ilat/10000 - 90

-- and print the results

lon = ilon/10000 - 180

printf(1,"\nAfter reversing the procedure:\n")

printf(1," latitude = %0.4f, longitude = %0.4f\n", {lat, lon})

-- and print the results

printf(1,"\nAfter reversing the procedure:\n")

printf(1," latitude = %0.4f, longitude = %0.4f\n", {lat, lon})</lang>

<pre>