HP 15C: Approximate Length of Sunlight During a Day

HP 15C:  Approximate Length of Sunlight During a Day

For the HP 35S version, please click here:

http://edspi31415.blogspot.com/2013/05/hp-35s-approximate-length-of-sunlight.html

Source: Total Daily Amount of Solar Radiation - HP 67/97 Energy Conservation Pac, December 1978, Author: Hewlett Packard

Instructions:

Y Stack:  Enter the latitude (North as positive, South as negative).  Use the D.MMSS (degrees-minutes-seconds) format

X Stack:  The number of days after March 21.  A 365 day year is assumed, as well as assuming March 21 is the vernal equinox.

Run the program.

This is an approximation.

Program:

Step	Key	Key Code
001	LBL E	42, 21, 5
002	DEG	43, 7
003	.	48
004	9	9
005	8	8
006	5	5
007	6	6
008	*	20
009	SIN	23
010	2	2
011	3	3
012	.	48
013	4	4
014	5	5
015	*	20
016	X<>Y	34
017	>H	43, 2
018	TAN	25
019	X<>Y	34
020	TAN	25
021	CHS	16
022	*	20
023	COS^-1  (ACOS)	43, 32
024	>RAD	42, 3
025	2	2
026	4	4
027	*	20
028	π	43, 26
029	÷	10
030	>H.MS	42, 2
031	RTN	43, 32

Example:

Los Angeles, April 17.  Latitude of 34°03’ N, 27 days after March 21. 

Result:  approximately 12.5735 (12 hours, 57 minutes, 35 seconds)

Sydney, June 21.  Latitude of 33°51’31” S (enter as -33.5131), 92 days after March 21. 

Result:  approximately 9.4439 (9 hours, 44 minutes, 39 seconds)

Rome, September 1.  Latitude of 41°51’ N, 164 days after March 21.

Result:  approximately 12.5323 (12 hours, 53 minutes, 23 seconds)

This blog is property of Edward Shore.  2016