d89-bfr@sm.luth.se (d89-bfr) (12/14/89)
Curve fitting programs.
How many times have you been annoyed by the fact that linear regression isn't
enough. These programs can handle polynomial, logarithmic and exponential
curves.
You have these samples
Y 4.0 17.0 62.0 157.0 569.0 320.0 1397.0 2012.0
X 1.0 2.0 3.0 4.0 6.0 5.0 8.0 9.0
I suspect that this is a polynomial function. Let's try.
Enter
[[1 5[
[2 17]
[3 62]
[4 157]
[6 569]
[5 320]
[8 1397]
[9 2012]
My guess is that it's a polynom of degree 4.
4 [PFIT]
[[5.00]
[-2.00]
[-2.00]
[3.00]
[3.88E-9]]
So. The furmula is, y=3*x^3-2*x^2-2*x+5.
Let's try enother curve.
Y 20 2.5 0.74 0.31
X 1 2 3 4 5 6
PFIT [7625]
<< SWAP TRN -> n s
<<
[[ 0 1 ]]
s * TRN
[[ 1 0 ]]
s * -> b sa
<< 1 sa SIZE 2
GET
FOR x 0 n
FOR p sa x
GET p ^
NEXT
NEXT sa SIZE 2
GET n 1 + 2 ->LIST
->ARRY DUP TRN -> a at
<< at b * at a
* /
>>
>>
>>
>>
LFIT [4715]
<< -> a
<< a SIZE LIST->
DROP -> r c
<< 1 r
FOR x 1 c
FOR y a x y
2 ->LIST GET LN a
SWAP x y 2 ->LIST
SWAP PUT 'a' STO
NEXT
NEXT a 1 PFIT
DUP 1 GET EXP 1 SWAP
PUT
>>
>>
>>
EFIT [D4DE]
<< -a
<< a SIZE LIST->
DROP -> r c
<< 1 r
FOR x a x 2 2
->LIST GET LN a SWAP
x 2 2 ->LIST SWAP PUT
'a' STO
NEXT a 1 PFIT
DUP 1 GET EXP 1 SWAP
PUT DUP 2 GET EXP 2
SWAP PUT
>>
>>
>>
No calculation of error yet. It might come in the future.
Have fun.
_
/Bjorn.