Displaying 2 results from an estimated 2 matches for "periodicty".
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periodicity
2010 Apr 18
4
confused with yearmon, xts and maybe zoo
...x <- x[-1, ] # drop
first obs (eg through na.omit)
index(xx) # starts
jan 2009
xxx <- xts(NA[1:length(xx)],index(xx)) # back to dec 2008
periodicity(x)
periodicity(xx)
periodicty(xxx)
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2010 Dec 20
2
Sine Regression in R
Hi everyone,
I am trying to fit a sine function on one year of wind data. I have two
questions below.
Looking around on the net I managed to get the following:
Sine Equation: y = a + b * sin( c + d*x )
b is the amplitude, c is the phase shift, d is something deal with
periodicty of data*.*
This can be linearised by sin( c+dx ) = cos(c) * sin(dx) + sin(c) *
cos(dx).
If one calls dx = x1
y = a + b * sin( c + d*x )
y = a + b * [cos(c) * sin(x1) + sin(c) * cos(x1)]
y = a + b * cos(c) * sin(x1) + b * sin(c) * cos(x1)
y = a + b1 * sin(x1) + b2 * cos(x1)
where b1 = b *...