fitting curve doed not work

[skjoex]

Hi,

I have a set of data in tabular form. I would like to fit a function over this set and then derive this function.

I have checked a manual and found I think appropriate commands - bspline and interp, but when plotted in one graph I can see it is not correct...

I usually use 1 as array origin, and knots of the spline are not equally spaced - do not even know if it is important for this case...

Right now I am not able to find an error. Please help !

 

[Occupant]

Why don't you use the attached, looks ok to me unless you want a better fit than that. You can easily put the coefficients into a polynomial function.

 

[pstuckey]

You don't define "t", so when you use it in the graph mathcad uses a default which is partially outside the range of your function. Try adding this line above the graph:

t:=0;42

which will define t as a range variable from 0 to 42 with step size of one.

Peter

 

[skjoex]

Thank you friends.