Usage

General Usage

Fitter is a C++ program aimed to fit a chosen theoretical multi-parameter function through a set of data points. The method of fitting is chi-square minimization. Moreover, the robust fitting method can be applied in Fitter. Fitter was designed to be used for a small-angle neutron scattering data analysis. Respective theoretical models are implemented in it. Some commonly used models (Gaussian and polynomials) are also implemented for wider applicability.

SYNOPSIS

fitter -{ std$\mathtt{\vert}$ sans$\mathtt{\vert}$ yumo} model [-s name] [-r] [-R x1:x2] [-v[ file]] [-o file] [-H file] [-rc-read] [-rc-write] file

fitter [-h] [-V]

INPUT

Input data file (ASCII) for fitter should have at least three columns: the first one would be interpreted by fitter as "X"-samples, second one - as "Y"-samples and the third one - as "Y"-errors. For YuMO models (see below) should be one more column, which is interpreted as "X"-errors.

OPTIONS

MODEL OPTIONS

-std model

Standard models. One of the following (see '-std help' for list):

g

Gaussian

e

Exponential

p0

Polynomial of the order 0

p1

Polynomial of the order 1

p2

Polynomial of the order 2

p3

Polynomial of the order 3

p4

Polynomial of the order 4

p5

Polynomial of the order 5

p6

Polynomial of the order 6

p7

Polynomial of the order 7

p8

Polynomial of the order 8

-sans model

SANS models. One of the following (see '-sans help' for list):

b

Ball

c

Cylinder

c2

Elliptical cylinder

e2

Two axis ellipsoid

p

Parallelepiped

ss

Spherical shell

-yumo model

SANS models for YuMO spectrometer. One of the following (see '-yumo help' for list):

b

Ball with resolution

c

Cylinder with resolution

c2

Elliptical cylinder with resolution

e2

Two axis ellipsoid with resolution

p

Parallelepiped with resolution

ss

Spherical shell with resolution

PROCESSING OPTIONS

-s, -strategy name

Change MINUIT strategy. MINIMIZE is a default one.

-r, -robust

Robust fitting. Useful for highly noised data.

-R, -range x1:x2

Fitting in range from x1 to x2. Note that no fit is applied if a range appearers to be empty.

-v, -verbose[ file]

Output MINUIT processing information. No output is produced by default. Repeating this option determines how much output will be produced:

1. minimum MINUIT output
2. normal MINUIT output
3. additional output giving intermediate results
4. maximum output, showing progress of minimizations

OUTPUT OPTIONS

-o, -output file

Output data file with the resulting theoretical curve. No file is created by default.

-H, -header file

Output resulting parameters and chi-square value to file (standard output by default). File may be the same as for theoretical curve, parameters and chi-square will be put to its beginning in this case.

-rc-read

Read rc-file. If specified, this option cause reading parameters staring values from rc-file. Some times this can highly speed-up minimization. Rc-file .fitter should exist in $HOME (in C: on Windows).

-rc-write

Write rc-file. If specified, this option cause writing resulting parameters to rc-file. Useful for creating/repairing rc-file. Rc-file .fitter is placed in $HOME (in C: on Windows).

HELP OPTIONS

-h, -help

Display short help message and exit.

-V, -version

Display version information and exit.

GUI

Fig. 2: Fitter's main window

Besides the command-line interface the Fitter offers an user friendly GUI (graphical user interface). Fitter's main window, shown in fig.2, is implemented in the standard manner with menu-bar, tool-bar and status-bar. All menu items exactly correspond to the command-line options described above. The command-line to be executed is just formed by choosing corresponding menu items and is displayed on the status-bar. Some of the most frequently used menu items are duplicated as buttons or combo-boxes on the tool-bar. A window with fitting results arises after fit is complete.