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Question: Definite integration of a spline function

Question:Definite integration of a spline function

Charles McCallum 12 Maple
September 27 2006
0
Hi there, I'm trying to integrate some experimental data. I'm sure that what I'm doing is not the best or most convenient way, but I think it should work. I read the data in using the import assistant, which put it into a 2d matrix. I then manipulated that matrix. This is heat capacity data (for those of you familiar with physical chemistry), and I'm baselining the h.c. data to zero before I integrate it. This hasn't presented any problems for me, and it (seems to) give the expected result. When I integrate this baselined data, however, the integrated curve (enthalpy) at low values of x is not close to zero; it is much bigger. The integrated curve's topology is what I'd expect, it is horizontal at small x values. It is just off of zero by some (large) constant. My data starts at about 300, ends at 360. Dnormspline := Spline(DNormdata, v, degree = 3) > Dnormplot := plot(Dnormspline, v = 303 .. 360); > DnormEnthalpy := int(Dnormspline, v); > DnormEplot := plot(DnormEnthalpy, v = 310 .. 360); I've found that messing with the "endpoints=[A,B]" option adjusts the overall position of the curve, but it is not clear to me why it should, or why that is valid, so I'd prefer not to be messing with that. I'm looking for obvious mistakes or misunderstanding in what I'm trying to do here. Cheers
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