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PIVMat 3.02

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PIVMat 3.02

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27 Apr 2006 (Updated )

A PIV Post-processing and data analysis toolbox

statf (PIVMat Toolbox)
statf (PIVMat Toolbox)
PIVMat Function Reference<< Prev | Next >> 
statf
Statistics of a vector/scalar field

Description
STAT = statf(F) returns a structure containing some statistics for the 
scalar field F. 
[STATX,STATY] = statf(F) returns two structures, each containing the 
statistics for the X,Y components of the 2-components vector field F. 
[STATX,STATY,STATZ] = statf(F) returns 3 structures, each containing 
the statistics for the X,Y,Z components of the 3-comp. vector field F. 
 
F is a structure (or structure array) of fields as obtained by loadvec 
(vector field) or vec2scal (scalar field). 
If F is a single field, the statistics are spatial averages. If F is 
an array of fields, the statistics combine spatial and ensemble averages. 
 
The output structure STAT (or STATX, STATY, STATZ) contains the 
following fields: 
  mean, std, rms:    mean, standard deviation and rms. 
  min, max:  minimum and maximum 
  nfields:   number of fields used in the computation 
  n:         number of nonzero elements. 
  zeros:     number of zero elements. 
  mom:       non-centered moments, <s^n> 
  momabs:    non-centered absolute moments, <|s^n|> 
  cmom:      centered moments, <(s-<s>)^n> 
  cmomabs:   centered absolute moments, <|s-<s>|^n> 
  skewness:  normalized 3rd order non-centered moment. (*) 
  flatness:  normalized 4th order non-centered moment. (*) 
  skewnessc: normalized 3rd order centered moment. (*) 
  flatnessc: normalized 4th order centered moment. (*) 
  history:   remind for which field statf has been called. 
 
In these definitions, the brackets <> denote both spatial and possibly 
ensemble averages. 
 
... = statf(F,MAXORDER) specifies the maximum order for the moments. 
MAXORDER=6 is used by default (although its convergence may not be 
guaranteed). The 4 quantities (*) are computed only if MAXORDER>2. 
 
If the fields contain 0 (zero) values, they are considered as 
erroneous and are not included into the computations. 
 
Examples
 
   v = loadvec('*.VC7'); 
   statrot = statf(vec2scal(filterf(v,1),'rot')); 
   statrot.rms 
 
See Also
loadvec, vec2scal, histf, corrf, vsf, specf. 
 
Published output in the Help browser 
   showdemo statf 

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