Horizontal sundial calculations: Difference between revisions
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m (→{{header|REXX}}: added/changed wording in the REXX section header, added/changed comments and whitespace, optimized the ATAN function.) |
m (→{{header|REXX}}: calculated the legal meridian instead of using a specified amount.) |
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The REXX language doesn't have the usual trigonometric functions, nor for that matter, a '''sqrt''' (square root) function, |
The REXX language doesn't have the usual trigonometric functions, nor for that matter, a '''sqrt''' (square root) function, |
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<br>so these as well as '''pi''' were added to this program. |
<br>so these as well as '''pi''' were added to this program. |
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The ''legal meridian''' is calculated instead of relying on a specified amount. |
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No attempt was made to explain the inner workings of the trigonometric functions. |
No attempt was made to explain the inner workings of the trigonometric functions. |
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<lang rexx>/*REXX program displays: hour, sun hour angle, dial hour line angle, 6am ───► 6pm. */ |
<lang rexx>/*REXX program displays: hour, sun hour angle, dial hour line angle, 6am ───► 6pm. */ |
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numeric digits 60 /*in case sundial is in polar regions. */ |
numeric digits 60 /*in case sundial is in polar regions. */ |
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parse arg lat lng |
parse arg lat lng . /*obtain optional arguments from the CL*/ |
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/* ┌───────────◄ None specified? Then use the default*/ |
/* ┌───────────◄ None specified? Then use the default*/ |
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/* │ of Jules Verne's Lincoln Island, */ |
/* │ of Jules Verne's Lincoln Island, */ |
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if lat=='' | lat=="," then lat= -4.95 /*Not specified? Then use the default.*/ |
if lat=='' | lat=="," then lat= -4.95 /*Not specified? Then use the default.*/ |
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if lng=='' | lng=="," then lng= -150.5 /* " " " " " " */ |
if lng=='' | lng=="," then lng= -150.5 /* " " " " " " */ |
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mer=format(lng/15, , 0) * 15 /*calculate legal meridian longitude. */ |
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sineLat=sin( d2r(lat) ) /*calculate sine of (radian) latitude. */ |
sineLat=sin( d2r(lat) ) /*calculate sine of (radian) latitude. */ |
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w1=max( length('hour' ), length("midnight" )) + 2 /*compute the max hour width.*/ |
w1=max( length('hour' ), length("midnight" )) + 2 /*compute the max hour width.*/ |
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