Function: floor235
FLOOR235  Previous number with only 2,3 and 5 factors
  Usage: nfloor=floor235(n);

  FLOOR235(n)  returns the next number greater than or equal to n,
  which can be written as a product of powers of 2, 3 and 5.

  The algorithm will look up the best size in a table, which is computed
  the first time the function is run. If the input size is larger than the
  largest value in the table, the input size will be reduced by factors of
  2, until it is in range.

  [nfloor,table]=FLOOR235(n) additionally returns the table used for lookup.

  Examples:
  ---------

  Return the first number smaller or equal to 26 that can be written
  solely as products of powers of 2, 3 and 5*:

    floor235(26)

  This plot shows the behaviour of FLOOR235 and CEIL235 for numbers
  up to 100:

    x=1:100;
    plot(x,floor235(x),x,ceil235(x));
    legend('floor235','ceil235','Location','Northwest');

Url: http://ltfat.github.io/doc/fourier/floor235.html

See also: floor23, ceil235, nextfastfft.

Package: ltfat