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reference:ft_math [2018/08/23 14:43] (current)
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 +=====  FT_MATH =====
 +
 +Note that this reference documentation is identical to the help that is displayed in MATLAB when you type "help ft_math"​.
 +
 +<​html><​pre>​
 +  <a href=/​reference/​ft_math><​font color=green>​FT_MATH</​font></​a>​ performs mathematical operations on FieldTrip data structures,
 +  such as addition, subtraction,​ division, etc.
 + 
 +  Use as
 +    data = ft_math(cfg,​ data1, data2, ...)
 +  with one or multiple FieldTrip data structures as the input and the configuration
 +  structure cfg in which you specify the mathematical operation that is to be
 +  executed on the desired parameter from the data
 +    cfg.parameter = string, field from the input data on which the operation is
 +                    performed, e.g. '​pow'​ or '​avg'​
 +    cfg.operation = string, for example '​(x1-x2)/​(x1+x2)'​ or '​x1/​6'​
 + 
 +  In the specification of the mathematical operation, x1 is the parameter obtained
 +  from the first input data structure, x2 from the second, etc.
 + 
 +  Rather than specifying the operation as a string that is evaluated, you can also
 +  specify it as a single operation. The advantage is that it is computed faster.
 +     ​cfg.operation = string, can be '​add',​ '​subtract',​ '​divide',​ '​multiply',​ '​log10',​ '​abs'​
 +  If you specify only a single input data structure and the operation is '​add',​
 +  '​subtract',​ '​divide'​ or '​multiply',​ the configuration should also contain:
 +    cfg.scalar ​   = scalar value to be used in the operation
 + 
 +  The operation '​add'​ is implemented as follows
 +    y = x1 + x2 + ....
 +  if you specify multiple input arguments, or as
 +    y = x1 + s
 +  if you specify one input argument and a scalar value.
 + 
 +  The operation '​subtract'​ is implemented as follows
 +    y = x1 - x2 - ....
 +  if you specify multiple input arguments, or as
 +    y = x1 - s
 +  if you specify one input argument and a scalar value.
 + 
 +  The operation '​divide'​ is implemented as follows
 +    y = x1 ./ x2
 +  if you specify two input arguments, or as
 +    y = x1 / s
 +  if you specify one input argument and a scalar value.
 + 
 +  The operation '​multiply'​ is implemented as follows
 +    y = x1 .* x2
 +  if you specify two input arguments, or as
 +    y = x1 * s
 +  if you specify one input argument and a scalar value.
 + 
 +  To facilitate data-handling and distributed computing you can use
 +    cfg.inputfile ​  ​= ​ ...
 +    cfg.outputfile ​ =  ...
 +  If you specify one of these (or both) the input data will be read from a *.mat
 +  file on disk and/or the output data will be written to a *.mat file. These mat
 +  files should contain only a single variable, corresponding with the
 +  input/​output structure.
 + 
 +  See also <a href=/​reference/​ft_datatype><​font color=green>​FT_DATATYPE</​font></​a>​
 +</​pre></​html>​