i4_uniform.m

function [ c, seed ] = i4_uniform ( a, b, seed )

%*****************************************************************************80
%
%% I4_UNIFORM returns a scaled pseudorandom I4.
%
%  Discussion:
%
%    The pseudorandom number will be scaled to be uniformly distributed
%    between A and B.
%
%  Parameters:
%
%    Input, integer A, B, the minimum and maximum acceptable values.
%
%    Input, integer SEED, a seed for the random number generator.
%
%    Output, integer C, the randomly chosen integer.
%
%    Output, integer SEED, the updated seed.
%
  i4_huge = 2147483647;

  if ( seed == 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'I4_UNIFORM - Fatal error!\n' );
    fprintf ( 1, '  Input SEED = 0!\n' );
    error ( 'I4_UNIFORM - Fatal error!' );
  end

  seed = floor ( seed );
  a = round ( a );
  b = round ( b );

  seed = mod ( seed, i4_huge );

  if ( seed < 0 ) 
    seed = seed + i4_huge;
  end 

  k = floor ( seed / 127773 );

  seed = 16807 * ( seed - k * 127773 ) - k * 2836;

  if ( seed < 0 )
    seed = seed + i4_huge;
  end

  r = seed * 4.656612875E-10;
%
%  Scale R to lie between A-0.5 and B+0.5.
%
  r = ( 1.0 - r ) * ( min ( a, b ) - 0.5 ) ...
    +         r   * ( max ( a, b ) + 0.5 );
%
%  Use rounding to convert R to an integer between A and B.
%
  value = round ( r );

  value = max ( value, min ( a, b ) );
  value = min ( value, max ( a, b ) );

  c = value;

  return
end