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COMMON blocks

The Computing for Science (CS) group supports ILL scientists, students and visitors in a number of activities including data analysis, instrument simulation and sample simulation.

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COMMON blocks used in FITFUN versions 5.4, 6.0, 7.x

R. Ghosh, 1998, 2010

The COMMON blocks listed here are used within FITFUN and contain values which might be useful to modellers. It is clear that modification of any of these COMMONs outside FITFUN may have disastrous consequences for the integrity of the package - please treat the contents in a "read-only" fashion. The only control options allowed concern re-entering fitfun:

Re-entering FITFUN


ICLOSE Integer default value 1
if set to 0 then the graphics channels remain open
and the calling program is resposible for the
CALL PGNEND(2) to close any hardcopy file correctly.

ISTART Integer default value 0
if set to 1 then the parameter file "pnam.par" is
not reread. Note problems will arise if
the initialisations are skipped first time!

         PARAMETER     v5.4        v6.0
MAXPAR 20 200

NAMES character*20 parameter names initialised by calling program
TX character*20 x-scale name initialised by calling program
TY character*20 y-scale name initialised by calling program

NPARAS integer number of parameters named

EXTRAT character*50 extra title (T command)

NPAR integer number of parameters used
PARM real parameter values
STEP real initial step multiplier (0 no fit)
SCALE real actual fitted variable (multiplier)

SDEV real % error in parameter at minimum
SDEW real error in scaled parameter
COVAR real normalised covariance matrix
COVAW real
IPAR integer number of fitted parameters

RF real fit R factor
RFOLD real fit R factor from previous fit
CHI real fit CHI factor
CHIOLD real fit CHI factor from previous fit
PROB real probability of fitting
NFREE integer degrees of freedom
NFITNO integer fit attempt number

INDEX integer maps parameter to fitted variable

INTTY integer READ unit for tty input
IOTTY integer WRITE unit for tty output
MNO integer number of reals read-in to VARIN
IERT integer error in read-in
VARIN integer real variables in last command input

PNAME character*4 name of program
RET character*1 last command input line

XLIMS real pairs of x limits for fitting
NSET integer number of regions to be fitted
MINF integer
MAXF integer
NFIT integer

XMIN real x-data minimum
XMAX real x-data maximum
YMIN real y-data minimum
YMAX real y-data maximum
XSCALE real plotting x min, max
YSCALE real plotting y min, max

NTX character*20 x-scale title for plot
NTY character*20 y-scale title
NTEX character*50 general title

XPL real extra x points for plotting extension of calc points
YPL real extra calculated y points for plotting
WERR real
WRK real
WRK1 real
NEXTRA integer number of extra points for plotting

DATSET logical true if data has been read in
PARSET logical true if parameters have been initialised
NEWDAT logical true if new data read in (reset chi etc)
PLTSET logical true if plot already on screen


XOBS real x read in
YOBS real y read in
YROBS real y-error read in
YER real
NDIN integer number of data read in

NPNT integer number of points selected for fit
XUSE real x values for used set of points
YUSE real y values for used set of points
YUSR real y-error for used set of points

YCALC real calculated values (in units of y)
F real derived difference (perhaps weighted)
to be minimised by fitfun

scrolling screen device
TEKTRO logical default false
true if screen has to be paged within fitfun

Fitfun version 7.x includes additional commons of interest
Fourth column read in
     COMMON/FLAGS4/INCOL4 INCOL4 (logical) set to .TRUE. - expect 4 column data
     COMMON/REDIT4/OBS4(MAXDAT)  (real) contains concatenated 4th column data from read-in routine
     COMMON/OBSDA4/USE4(MAXDAT)  (real) selected 4th column data for calculation