3-d order derivative
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Dear all,
there is the following problem with the calculation of a 3-d order derivative.
I have two vectors of lambda and refractive index, respectively. I take the 3-d order derivative using a gradient().
dndl=gradient(n)./gradient(lambda);
d2ndl2=gradient(dndl)./gradient(lambda);
d3ndl3=gradient(d2ndl2)./gradient(lambda);
When I use a relatively small number of points (for example 3000) , I get a smooth plot.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/893025/image.jpeg)
In the case of more points (30 000) there is some oscillation in the plot.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/893030/image.jpeg)
What is the reason of such behavior?
Thank you a lot.
댓글 수: 2
Matt J
2022년 2월 13일
What do you mean by "use more points"? If it's a different input array why expect the same results?
답변 (3개)
Catalytic
2022년 2월 13일
If the points are too close together, the difference between neighbours will be so small as to be dominated by floating point errors
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