vector gives 0 integral

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Hello
I have plotted a vector which has 3 planes.. When I integrate the integral is 0. There are negative regions, yet I expect a number. I us
sd = trapz((z),0,20)
sd =
0
will someone tell me if there is an error with my use of trapz?
sr

Accepted Answer

Star Strider
Star Strider on 28 Jul 2021
There quite definitely is!
In your call to it:
sd = trapz((z),0,20)
the function interprets ‘z’ (the parentheses aren’t necessary) as the indepdent variable ‘x’, 0 as the dependent variable ‘y’, and 20 as the dimension. Integrating 0 produces 0 as the result.
See the documentation on trapz.
.
  30 Comments
Star Strider
Star Strider on 3 Nov 2021
That expression is a function of ‘x’, so provide a value for it (scalar, vector, using subs if necessary), evaluate it, then print the double result as a funciton of the values of ‘x’.
.

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More Answers (3)

Gavin Seddon
Gavin Seddon on 29 Jul 2021
Hello
Yes John is correct, I tried with no parenth and I see the fun integral not its value which is wht I need.
  4 Comments
Star Strider
Star Strider on 29 Jul 2021
Thank you!
Just curious as to what you are integrating.
.

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Gavin Seddon
Gavin Seddon on 29 Jul 2021
Hello
When I searched 'vector integration' the trapezoid method came-up
yet is this correct?

Gavin Seddon
Gavin Seddon on 4 Aug 2021
Hello
I am integrating the number of molecular motions in 10e-15s.

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