I was trying to reproduce this failure, but I think you may have
forgotten to add something. What is V?
Thanks - hopefully we can get to the bottom of this.
- kcrisman
On Nov 13, 6:21 pm, Aran <arant...@freenet.de> wrote:
> I'm using sage for data analysis and number crunching in my physical
> chemistry class and stumbled on a curiosity while replacing the
> variables that are used by find_fit:
>
> When replacing variables like 'a, b ,c' for 'c1, c2, c3' on a 11th
> degree polynomial the whole find_fit-function goes nuts and the former
> nicely fitting function doesn't fit at all anymore.
>
> Example:
> While the following code works perfectly:
>
> var('a b c d f g j h k l n o')
> model(x) = a*x
> +b*x^(2)+c*x^(3)+d*x^(4)+f*x^(5)+g*x^(6)+h*x^(7)+j*x^(8)+k*x^(9)+l*x^(10)+n
> *x^(11)+o
> m=find_fit(V,model)
> Temp(x)=model(a=m[0].rhs(),b=m[1].rhs(),c=m[2].rhs(),d=m[3].rhs(),f=m[4].rh
> s(),g=m[5].rhs(),h=m[6].rhs(),j=m[7].rhs(),k=m[8].rhs(),l=m[9].rhs(),n=m[10
> ].rhs(),o=m[11].rhs())
>
> The following code does not (replaced only 'a' by 'k1') and Temp(x)
> shoots off to infinity at some point:
>
> var('k1 b c d f g j h k l n o')
> model(x) = k1*x
> +b*x^(2)+c*x^(3)+d*x^(4)+f*x^(5)+g*x^(6)+h*x^(7)+j*x^(8)+k*x^(9)+l*x^(10)+m
> *x^(11)+o
> m=find_fit(V,model)
> Temp(x)=model(k1=m[0].rhs(),b=m[1].rhs(),c=m[2].rhs(),d=m[3].rhs(),f=m[4].r
> hs(),g=m[5].rhs(),h=m[6].rhs(),j=m[7].rhs(),k=m[8].rhs(),l=m[9].rhs(),n=m[1
> 0].rhs(),o=m[11].rhs())
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