trapz step size

[Pg]

Hi,

I want to use numerical integration command trapz. My data is a vector and n't a function. and I want to fix a step size other than 1. How to fix this step size as in help menu it is written I need to multiply the output with step size, which I couldn't understood. If any body shows any script file will be quite helpful for me.

[Steven_Lord]

"Pg " <poulo...@gmail.com> wrote in message
news:iltdj1$d33$1...@ginger.mathworks.com...

Let's look at the reference page for TRAPZ.

http://www.mathworks.com/help/techdoc/ref/trapz.html

The section you're citing is:

"Z = trapz(Y) computes an approximation of the integral of Y via the
trapezoidal method (with unit spacing). To compute the integral for spacing
other than one, multiply Z by the spacing increment. Input Y can be
complex."

Note that this ONLY applies to the 1-input form of TRAPZ. The corresponding
line for the 2-input form of TRAPZ makes no mention of spacing, as TRAPZ can
determine the spacing from the X vector.

"Z = trapz(X,Y) computes the integral of Y with respect to X using
trapezoidal integration. Inputs X and Y can be complex."

Therefore I recommend you construct your X and Y vectors and pass them both
into TRAPZ as is done in all three of the examples on the reference page.
Example 1 uses a uniform spacing (with a step size other than 1) between the
data points; example 2 uses nonuniform spacing between the points.

--
Steve Lord
sl...@mathworks.com
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