Eval15 lambda

A simulation (simulate>0) will need values of the wavelength. There are various constants to control the wavelength spectrum.

The spectrum

The spectrum consists of one or more wavelength records. Each wavelength record contains

Lambda
The wavelength
Sigma
A measure of the distribution width of the wavelength. The interpretation depends on the value of lambdatype (gauss, lor or block).
Weight
A relative weight of the wavelength. The weight is the integral of the distribution of the wavelength. If you double for example the sigma the relative peakheight will be halved.
Low
The lowest value of the wavelength during simulation. A negative value corresponds to no lower limit.
High
The highest value of the wavelength during simulation. A negative Low corresponds to no upper limit.
Type
Sets the distrution type of the wavelength. One of gauss, lor or block.

Mean and mid

eval15 uses the value of weighted mean (λ_mean) and unweighted mean (λ_mid) for various purposes.

λ_mean
Used for the determination of the resolution of a reflection.
λ_mid
Used the calculate the central impact of a reflection. The central impact uses λ_mid, a pointfocus, a zero-sized crystal and a mosaicity of zero.

If you set the spectrum with the target, λ_mean and λ_mid are calculated using α₁ and α₂. You can set the values of λ_mean and λ_mid with lambdameanmid or calculate them with lambdacalcmean.

How to define the spectrum

lambdainit
Clears the wavelength spectrum
detectortype
Every detectortype has a default target.
target
Sets alpha1 and alpha2 according to the target material using:
- lambdainit
- lambdaadd α₁ 0 2
- lambdaadd α₂ 0 1
lambdaadd
Add a new wavelength with corresponding sigma and weight to the spectrum.
lambdaaddfull
Add a new wavelength with corresponding sigma, weight, minimum, maximum and type to the spectrum.
Using boxfiles: the wavelength will be set to the value found in the boxfile. But if you have used one the the following commands, the wavelength information from the boxfile will be ignored: lambdaadd, lambdacalcmean, lambdavalue.

How to change the spectrum

lambdaadd
Adds a new wavelength record.
lambdaaddfull
Adds a new wavelength record.
lambdavalueX
Allows you to change the lambda field in a wavelength record
lambdasigmaX
Allows you to change the sigma field in a wavelength record
lambdaweightX
Allows you to change the weight field in a wavelength record
lambdalowX
Allows you to change the lower limit in a wavelength record
lambdahighX
Allows you to change the upper limit in a wavelength record
lambdatypeX
Allows you to change the type field in a wavelength record
lambdavalueall
Set the lambda fields for all wavelength records
lambdasigmaall
Sets the sigma fields in all wavelength records
lambdatypeall
Sets the type fields in all wavelength records
lambdaweightall
Sets the weight fields in all wavelength records
lambdalowall
Sets the lower limits in all wavelength record
lambdahighall
Sets the upper limits in all wavelength record
lambdameanmid
Sets the weighted and unweighted average wavelengths.
lambdacalcmean
Calculate the weighted and unweighted average wavelengths.
onescan lambda X
calculate fom for varying wavelength
onescan lamsig X
calculate fom for varying wavelength sigma
onescan lamwght X
calculate fom for varying wavelength weight

How to examine the spectrum

Use the distribution plot command.
- Set distribution type lambda
- The Distribution Window will be created. The window dimensions are calculated from the screen dimensions and the value of distribution fraction (width=distribution fraction*screenwidth, height=0.5*distribution fraction*screenheight).
  But you may specify your own window dimensions with the command distribution size.
- The spectrum will be plotted between fmin and fmax.. fmin is the value of λ_min minus 5 times the corresponding sigma. fmax is the value of λ_max plus 5 times the corresponding sigma. (if the sigma's are small or even zero, fmin will be set to λ_min - 0.1 * (λ_max-λ_min) and fmax to λ_max + 0.1 * (λ_max - λ_min).
  But you may define your own boundary limits by setting distribution autolimit off and specifying distribution limit
- The wavelength select routine will generate wavelengths from the spectrum. These wavelengths are converted to integers, and a histogram of these integers is build. the changed bin in the histogram will be plotted so the progress of this process can be followed.
- This process continues until the highest bin in the spectrum reaches distribution peak.
lambdaprint
show lambda

Eval15
Eval15 commands