1 ACCEPTED SOLUTION
Accepted Solutions
Afterthought:
If you really want the coefficients and need a symbolic representation, you can either use regression as shown by Valery Ochkov or you can use polyfitc which you already mentioned yourself.
If you want to show this function via symbolic evaluation (why would you do so?), you have to add a numeric evaluation after the definition of coeffs, because the symbolics can not evaluate poyfitc.
The symbolics are unit unaware and treats time and volume units like unknown variables. I guess you could replace s and m by min and L using substitute.
Concerning the help pages: I would suggest you install Mathcad 15 (you get it for free with Prime) and use the help of that program. Is not complete either but much better accessible compared to what Prime offers.
Why do you try a fit with a polynomial of that high order? Do you know that the data should follow a polynomial? You could try a polynomial with much smaller degree (e.g. 3) or a logistic regression (assuming that the decrease at the end should not be there). It all depends on where the data stems from, what is represents and what you know about it.
Is it mandatory to fit with a continuous, analytic function, or wouldn't a simple linear or a spline interpolation do the job as well? You can integrate those interpolations numerically as well.
You won't need the coefficients of the polynomial if all you wanna do is plotting, numerical integration, etc. Just use your function g(x) the usual way as you already did in the plot:
You should replace the second zero in your X-vector for a different value like 2 for consistency.
I wonder why polyfit does not throw an error because of the two equal x-values.
What happened to this site? Looks like it was undergoing heavy changes in appearance and functionality. Navigation looks a bit more straightforward but the overall visual impact is less appealing and overburdened compared to what I remember. Not very inviting.
Afterthought:
If you really want the coefficients and need a symbolic representation, you can either use regression as shown by Valery Ochkov or you can use polyfitc which you already mentioned yourself.
If you want to show this function via symbolic evaluation (why would you do so?), you have to add a numeric evaluation after the definition of coeffs, because the symbolics can not evaluate poyfitc.
The symbolics are unit unaware and treats time and volume units like unknown variables. I guess you could replace s and m by min and L using substitute.
Concerning the help pages: I would suggest you install Mathcad 15 (you get it for free with Prime) and use the help of that program. Is not complete either but much better accessible compared to what Prime offers.
Why do you try a fit with a polynomial of that high order? Do you know that the data should follow a polynomial? You could try a polynomial with much smaller degree (e.g. 3) or a logistic regression (assuming that the decrease at the end should not be there). It all depends on where the data stems from, what is represents and what you know about it.
Is it mandatory to fit with a continuous, analytic function, or wouldn't a simple linear or a spline interpolation do the job as well? You can integrate those interpolations numerically as well.
