vector gives 0 integral

9 views (last 30 days)
Gavin Seddon on 28 Jul 2021
Commented: Star Strider on 3 Nov 2021
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

Star Strider on 28 Jul 2021
There quite definitely is!
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.
.
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’.
.

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.
Star Strider on 29 Jul 2021
Thank you!
Just curious as to what you are integrating.
.

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

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

R2021a

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