Info Catalog octave: Trigonometry octave: Arithmetic octave: Utility Functions

octave: Sums and Products

 
 17.4 Sums and Products
 ======================
 
  -- : sum (X)
  -- : sum (X, DIM)
  -- : sum (..., "native")
  -- : sum (..., "double")
  -- : sum (..., "extra")
      Sum of elements along dimension DIM.
 
      If DIM is omitted, it defaults to the first non-singleton
      dimension.
 
      The optional "type" input determines the class of the variable used
      for calculations.  If the argument "native" is given, then the
      operation is performed in the same type as the original argument,
      rather than the default double type.
 
      For example:
 
           sum ([true, true])
              ⇒ 2
           sum ([true, true], "native")
              ⇒ true
 
      On the contrary, if "double" is given, the sum is performed in
      double precision even for single precision inputs.
 
      For double precision inputs, the "extra" option will use a more
      accurate algorithm than straightforward summation.  For single
      precision inputs, "extra" is the same as "double".  Otherwise,
      "extra" has no effect.
 
DONTPRINTYET       See also: cumsum XREFcumsum, sumsq XREFsumsq, *noteDONTPRINTYET       See also: cumsum XREFcumsum, sumsq XREFsumsq, 
      prod XREFprod.
 
  -- : prod (X)
  -- : prod (X, DIM)
  -- : prod (..., "native")
  -- : prod (..., "double")
      Product of elements along dimension DIM.
 
      If DIM is omitted, it defaults to the first non-singleton
      dimension.
 
      The optional "type" input determines the class of the variable used
      for calculations.  If the argument "native" is given, then the
      operation is performed in the same type as the original argument,
      rather than the default double type.
 
      For example:
 
           prod ([true, true])
              ⇒ 1
           prod ([true, true], "native")
              ⇒ true
 
      On the contrary, if "double" is given, the operation is performed
      in double precision even for single precision inputs.
 
      See also: cumprod XREFcumprod, sum XREFsum.
 
  -- : cumsum (X)
  -- : cumsum (X, DIM)
  -- : cumsum (..., "native")
  -- : cumsum (..., "double")
      Cumulative sum of elements along dimension DIM.
 
      If DIM is omitted, it defaults to the first non-singleton
      dimension.  For example:
 
           cumsum ([1, 2; 3, 4; 5, 6])
              ⇒  1   2
                  4   6
                  9  12
 
      See ‘sum’ for an explanation of the optional parameters "native"
      and "double".
 
      See also: sum XREFsum, cumprod XREFcumprod.
 
  -- : cumprod (X)
  -- : cumprod (X, DIM)
      Cumulative product of elements along dimension DIM.
 
      If DIM is omitted, it defaults to the first non-singleton
      dimension.  For example:
 
           cumprod ([1, 2; 3, 4; 5, 6])
              ⇒  1   2
                  3   8
                 15  48
 
      See also: prod XREFprod, cumsum XREFcumsum.
 
  -- : sumsq (X)
  -- : sumsq (X, DIM)
      Sum of squares of elements along dimension DIM.
 
      If DIM is omitted, it defaults to the first non-singleton
      dimension.
 
      This function is conceptually equivalent to computing
 
           sum (x .* conj (x), dim)
 
      but it uses less memory and avoids calling ‘conj’ if X is real.
 
      See also: sum XREFsum, prod XREFprod.
 

Info Catalog octave: Trigonometry octave: Arithmetic octave: Utility Functions