Air mass: Difference between revisions
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:* Do the same for the SOFIA infrared telescope, which has an orbiting altitude of 13,700 meters. |
:* Do the same for the SOFIA infrared telescope, which has an orbiting altitude of 13,700 meters. |
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<br><br> |
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=={{header|Factor}}== |
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{{trans|FreeBASIC}} |
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{{works with|Factor|0.99 2021-02-05}} |
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<lang factor>USING: formatting io kernel math math.functions math.order |
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math.ranges math.trig sequences ; |
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CONSTANT: RE 6,371,000 ! Earth's radius in meters |
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CONSTANT: dd 0.001 ! integrate in this fraction of the distance already covered |
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CONSTANT: FIN 10,000,000 ! integrate to a height of 10000km |
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! the density of air as a function of height above sea level |
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: rho ( a -- x ) neg 8500 / e^ ; |
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! z = zenith angle (in degrees) |
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! d = distance along line of sight |
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! a = altitude of observer |
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:: height ( a z d -- x ) |
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RE a + :> AA |
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AA sq d sq + 180 z - deg>rad cos AA * d * 2 * - sqrt RE - ; |
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:: column-density ( a z -- x ) |
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! integrates along the line of sight |
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0 0 :> ( s! d! ) |
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[ d FIN < ] [ |
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dd dd d * max :> delta ! adaptive step size to avoid taking it forever |
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s a z d 0.5 delta * + height rho delta * + s! |
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d delta + d! |
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] while s ; |
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: airmass ( a z -- x ) |
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[ column-density ] [ drop 0 column-density ] 2bi / ; |
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"Angle 0 m 13700 m" print |
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"------------------------------------" print |
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0 90 5 <range> [ |
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dup [ 0 swap airmass ] [ 13700 swap airmass ] bi |
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"%2d %15.8f %17.8f\n" printf |
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] each</lang> |
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{{out}} |
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<pre> |
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Angle 0 m 13700 m |
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------------------------------------ |
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0 1.00000000 1.00000000 |
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5 1.00380963 1.00380965 |
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10 1.01538466 1.01538475 |
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15 1.03517744 1.03517765 |
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20 1.06399053 1.06399093 |
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25 1.10305937 1.10306005 |
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30 1.15418974 1.15419083 |
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35 1.21998076 1.21998246 |
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40 1.30418931 1.30419190 |
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45 1.41234169 1.41234567 |
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50 1.55280404 1.55281025 |
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55 1.73875921 1.73876915 |
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60 1.99212000 1.99213665 |
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65 2.35199740 2.35202722 |
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70 2.89531368 2.89537287 |
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75 3.79582352 3.79596149 |
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80 5.53885809 5.53928113 |
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85 10.07896219 10.08115981 |
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90 34.32981136 34.36666557 |
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</pre> |
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=={{header|FreeBASIC}}== |
=={{header|FreeBASIC}}== |
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