multiexp
multiexp fcn_file_name
minuit
prompt (see section 4)
scale = scale_value
scale = 2.44
maxdelta = max_delta_value
lambda_corr λ0 c0 c1 c2 ...
save data "filename"
data
on a file. Writing to files is performed
when the user calls the standard
command at the minuit
prompt. But
the definition of the file names must be performed in FCN file.
data
can be graph
, tau
,
gpfile
. By default, files are not saved;
they are not saved also if file name is a null string "".
graph
generates a file with one block for each F, with four
columns: λ, F value, best fit, IRF.
tau
contains all the parameter values.
gpfile
is a gnuplot command file, that can read "tau" and generate a graph
with the DAS.
load decay "filename" [ (from-to) ] lambda time
load IRF "filename" [ (from-to) ]
load IRF
command must be issued before all the
load decay"
that have that IRF. For example:
load IRF "irfA.txt"
load decay "decay1_irfA.txt" 650 100
load decay "decay2_irfA.txt" 670 100
load decay "decay3_irfA.txt" 690 100
load IRF "irfB.txt"
load decay "decay1_irfB.txt" 650 100
load decay "decay2_irfB.txt" 670 100
load decay "decay3_irfB.txt" 690 100
The first group of decays has been measured with a given setup, and its IRF has been saved as "irfA.txt". Then, a second group of measures has been performed, with a different setup, and its IRF has been saved as "irfB.txt".
The (from-to) can be optionally appended to the command, in order to define which lines must be processed.
For "decay" measurements, "lambda" and "time" must be defined. "lambda" will be used for lambda_corr (if any), while "time" will be used to normalize the resulting A.
The files with data must contain a column of numbers, representin the counts in each bin. Negative values are excluded from the fit. It's worth noting that a poissonian error is assumed for every count in a bin, and is evaluated as the square root of the counts. So do not normalize or multiply the counts by any amount.
basename "base_name"
basename "data/"
load decay "d1.txt" 680 10
loads the file "data/d1.txt"
. This command can be issued
anywhere; it has effect until another basename
command is
issued. To stop the effect of a basename
command, use
basename ""
load decay "test"".txt" 680 10
Minuit
commandsminuit
commands:
set title
Test
parameter
1 'tau1' 3000.0 100.3 0 10000
2 'tau2' 149.0 10.0 0 500
3 'tau3' 63.0 2.0 0 200
4 'tau4' 12.0 0.2 0 100
fix 1
minimize
standard
exit
When a new tauN is defined, an exponential is added to the fitting function. It is not necessary to define A, b and δ. If they are defined, they can be fixed to any value, and error evaluation can be performed. Anyhow, their value is always calculated, also if the parameter doesn't appear anywhere.
If a parameter has been defined but it is no more needed, it can be overwritten with
a new parameter. For example, if parameter 3 is A2-3
, you can do:
> param
> 3 'A2-1' 0.02 0.01
> (remember to press <ENTER> in this line before writing other commands)
If no other parameter is needed, minuit
gives no way to delete it.
Multiexp
gives a way to make it harmless: it must be overwritten with a new parameter
called 'null1'
or similar; the value is not important; moreover, the
parameter must be set 'fix'. For example, if parameter 3 is no more needed:
> param
> 3 'null1' 2 1
> (remember to press <ENTER> in this line before writing other commands)
> fix 3
Multiexp
accepts parameters like 'null1', 'null2' and so on, and neglects
their value; setting them 'fix' prevents minuit
from performing any calculation on them.
The parameters τ must be always different from one another. If you define two of them with the same value, you will likely obtain a "singular matrix" error, that means you have a manifold of solutions.
The parameters A are the amplitude of the exponential function in which the measured function is decomposed, with a normalization constant. The normalization constant contains the following terms:
The user should never define UP with "set err 13.5" or similar. The correct value of UP is defined by the program in order to give the 68% confidence.
The command standard performs the following operations:
save
command in FCN file.
make
in a shell.