Horizontal sundial calculations: Difference between revisions
Content added Content deleted
(J: avoid principal value issue) |
(J: rephrase to highlight use of atan2) |
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<lang j>require 'trig' |
<lang j>require 'trig' |
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atan2=: {:@*.@j. NB. arc tangent of y divided by x |
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horiz=: verb define |
horiz=: verb define |
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'lat lng ref'=. y |
'lat lng ref'=. y |
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'Diff longitude ' out -diff=. ref - lng |
'Diff longitude ' out -diff=. ref - lng |
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lbl=.'hour ';'sun hour angle ';'dial hour line angle' |
lbl=.'hour ';'sun hour angle ';'dial hour line angle' |
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r=.((,. (,. ( |
r=.((,. (,. (atan2 *&slat)/@+.@r.&.rfd)) diff + 15&*) i:6 |
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smoutput lbl ,: ('3.0';'7.3';'7.3') 8!:1 r |
smoutput lbl ,: ('3.0';'7.3';'7.3') 8!:1 r |
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)</lang> |
)</lang> |
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