12-14-2013, 07:20 PM
FIRST METHOD:
'ALIG'
A(a,a'), B(b,B'), C(c,c') are lined up if the determinant = 0
|a a' 1|
|b b' 1| = 0
|c c' 1|
SECOND METHOD: (added 26/12/2013)
A(a,a'), B(b,B'), C(c,c') are lined up if the angle (AB,AC) = 0 modulo π (in radians)
Lets find the angle (AB,AC) first
'ANGL'
then
'ALIG'
Examples:
3: (2,2)
2: (4,1)
1: (5,3)
ALIG
1: 0 (false)
3: (2,-3)
2: (4,1)
1: (5,3)
ALIG
1: 1 (true)
Code:
« C→R 1
4 ROLL C→R 1
7 ROLL C→R 1
{3 3} →ARRY DET
ABS 1E-10 <
»
A(a,a'), B(b,B'), C(c,c') are lined up if the determinant = 0
|a a' 1|
|b b' 1| = 0
|c c' 1|
SECOND METHOD: (added 26/12/2013)
A(a,a'), B(b,B'), C(c,c') are lined up if the angle (AB,AC) = 0 modulo π (in radians)
Lets find the angle (AB,AC) first
Code:
« 3 PICK -
ARG
SWAP ROT -
ARG -
1 SWAP R→C
P→R ARG
»
then
Code:
« ANGL
2 *
1 SWAP R→C
P→R ARG
ABS 1E-10 <
»
Examples:
3: (2,2)
2: (4,1)
1: (5,3)
ALIG
1: 0 (false)
3: (2,-3)
2: (4,1)
1: (5,3)
ALIG
1: 1 (true)