HP 15C: Coordinates
on an Ellipse
Store the following values before running:
R0 = number of points.
θ always starts at 0° to 360° in equal increments.
R1 = a, length of horizontal semi-axis
R2 = b, length of vertical semi-axis
R3 is used as a counter.
The center is assumed to be (0,0).
Program:
|
Step
|
Key
|
Key Code
|
|
001
|
LBL B
|
42, 21, 12
|
|
002
|
DEG (Degrees mode)
|
43, 7
|
|
003
|
RCL 0
|
45, 0
|
|
004
|
1
|
1
|
|
005
|
-
|
30
|
|
006
|
3
|
3
|
|
007
|
10^X
|
13
|
|
008
|
÷
|
10
|
|
009
|
STO 3
|
44, 3
|
|
010
|
3
|
3
|
|
011
|
6
|
6
|
|
012
|
0
|
0
|
|
013
|
RCL÷ 0
|
45, 10, 0
|
|
014
|
STO 4
|
44 ,4
|
|
015
|
LBL 2
|
42, 21, 2
|
|
016
|
RCL 3
|
45, 3
|
|
017
|
INT
|
43, 44
|
|
018
|
R/S
|
31
|
|
019
|
RCL* 4
|
45, 20, 4
|
|
020
|
ENTER
|
36
|
|
021
|
COS
|
24
|
|
022
|
RCL* 1
|
45, 20, 1
|
|
023
|
R/S
|
31
|
|
024
|
X<>Y
|
34
|
|
025
|
SIN
|
23
|
|
026
|
RCL* 2
|
45, 20, 2
|
|
027
|
R/S
|
31
|
|
028
|
ISG 3
|
42, 6, 3
|
|
029
|
GTO 2
|
22, 2
|
|
030
|
RTN
|
43, 32
|
Outputs:
Point number (0 through n-1), [ R/S ]
X coordinate [ R/S ],
Y coordinate [ R/S ]
The program continues until all the points are revealed.
Example:
R0 = 6, R1 =
1.2500, R2 = 2.4700 (FIX 4 mode)
|
Point #
|
X
|
Y
|
|
0
|
1.2500
|
0.0000
|
|
1
|
0.6250
|
2.1391
|
|
2
|
-0.6250
|
2.1391
|
|
3
|
-1.2500
|
0.0000
|
|
4
|
-0.6250
|
-2.1391
|
|
5
|
0.6250
|
-2.1391
|