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Confused by Integration
From: |
Jason C. Wells |
Subject: |
Confused by Integration |
Date: |
Sun, 14 Aug 2011 15:27:23 -0700 |
User-agent: |
Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.13) Gecko/20110120 Lightning/1.0b2 Thunderbird/3.1.7 |
I am confused by integration. I see that the various quad function take
different types (scalar, vector) and give different outputs. I've been
trying them out and watching how the quadrature behaves for each of
them. E.g:
function retval = integrand (x)
x
retval = x .^ 2
endfunction
# integral = quadv ("integrand", -Inf, Inf)
a = -10: 1: 10;
integral = quadgk ("integrand", a(1), a(end))
Quadgk seems close to what I want, but the variable of integration
"bounces around" which makes plotting impossible.
x=
-9.999989
-9.435377
-7.911791
-5.669229
-2.947694
0.012817
2.972302
5.690762
7.928196
Ultimately I'd like to make a plot of the integral. It seems that all
of the quadrature functions do not pay attention to the the range i've
given. The functions do their own thing within the limits of integration.
Does a person need to run the integration, then re-sort and
re-interpolate in order to produce outputs at evenly spaced inputs?
How do I integrate such that each output value corresponds with an input
value taken from a range of from a linspace vector?
Thanks in advance,
Jason C. Wells
- Confused by Integration,
Jason C. Wells <=