## Numerical Integration/Differentiation in R: FTIR Spectra

Submitted by dylan on Tue, 2010-02-23 21:42.

Stumbled upon an excellent example of how to perform numerical integration in R. Below is an example of piece-wise linear and spline fits to FTIR data, and the resulting computed area under the curve. With a high density of points, it seems like the linear approximation is most efficient and sufficiently accurate. With very large sequences, it may be necessary to adjust the value passed to the subdivisions argument of integrate(). Strangely, larger values seem to solve problems encountered with large datasets...

FTIR Spectra Integration

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## Example XRD plot 2

Submitted by dylan on Mon, 2007-12-17 05:51.

illustrating common d-spacings

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## Example XRD plot with lattice graphics

Submitted by dylan on Mon, 2007-12-17 00:10.

7 horizons and 5 treatments

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## Plotting XRD (X-Ray Diffraction) Data

Submitted by dylan on Mon, 2007-12-17 00:04.

Premise:

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## Multi-horizon XRD sample plot 2

Submitted by dylan on Thu, 2005-12-08 08:20.

MG and MG+GLY treatments vs. K treatment for an entire soil profile.

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## Multi-horizon XRD sample plot 1

Submitted by dylan on Thu, 2005-12-08 08:18.

three potassium treatments for all horizons of a soil profile

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## Two-page display of XRD data for an entire soil profile

Submitted by dylan on Thu, 2005-12-08 08:18.
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## Some ideas on annotating common d-spacings

Submitted by dylan on Mon, 2005-11-28 05:24.

## note that we need to define this function before we can use it
## put all of the plotting commands into a wrapper function:
plot_xrd <- function(d)
{

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## Quick trip to the Ione formation

Submitted by dylan on Sun, 2005-06-26 19:20.