<s>
Fityk	B-Language
is	O
curve	B-Algorithm
fitting	I-Algorithm
and	O
data	O
analysis	O
application	O
,	O
predominantly	O
used	O
to	O
fit	O
analytical	O
,	O
</s>
<s>
Originally	O
,	O
Fityk	B-Language
was	O
developed	O
to	O
analyse	O
powder	O
diffraction	O
data	O
.	O
</s>
<s>
Fityk	B-Language
is	O
free	O
and	O
open	O
source	O
,	O
distributed	O
under	O
the	O
terms	O
of	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
,	O
with	O
binaries/installers	O
available	O
free	O
of	O
charge	O
on	O
the	O
project	O
's	O
website	O
.	O
</s>
<s>
It	O
runs	O
on	O
Linux	B-Application
,	O
macOS	B-Application
,	O
Microsoft	B-Application
Windows	I-Application
,	O
FreeBSD	B-Operating_System
and	O
other	O
platforms	O
.	O
</s>
<s>
It	O
operates	O
either	O
as	O
a	O
command	B-Application
line	I-Application
program	O
or	O
with	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
It	O
is	O
written	O
in	O
C++	B-Language
,	O
using	O
wxWidgets	B-Language
,	O
and	O
providing	O
bindings	O
for	O
Python	B-Language
and	O
other	O
scripting	B-Language
languages	I-Language
.	O
</s>
<s>
three	O
weighted	B-Algorithm
least	I-Algorithm
squares	I-Algorithm
methods	O
:	O
</s>
<s>
Levenberg-Marquardt	B-Algorithm
algorithm	I-Algorithm
,	O
</s>
<s>
The	O
programs	O
LabPlot	B-Language
,	O
MagicPlot	B-Application
and	O
peak-o-mat	O
have	O
similar	O
scope	O
.	O
</s>
<s>
More	O
generic	O
data	O
analysis	O
programs	O
with	O
spread-sheet	O
capabilities	O
include	O
the	O
proprietary	O
Origin	B-Application
and	O
its	O
clones	O
QtiPlot	B-Language
(	O
paid	O
,	O
closed	O
source	O
)	O
and	O
SciDAVis	B-Language
(	O
non-paid	O
,	O
open	O
source	O
)	O
.	O
</s>
