# include <stdlib.h>
# include <stdio.h>

float fran ( float a, float b, int *seed )

//
//  Purpose:
//
//    FRAN returns a scaled pseudorandom float between A and B.
//
//  Parameters:
//
//    Input, float A, B, the limits of the interval.
//
//    Input/output, int *SEED, the "seed" value, which should NOT be 0.
//    On output, SEED has been updated.
//
//    Output, float FRAN, a number between A and B.
//
{
  int i4_huge = 2147483647;
  int k;
  float value;
//
//  Check SEED.
//
  if ( *seed == 0 )
  {
    printf ( "\n" );
    printf ( "FRAN - Fatal error!\n" );
    printf ( "  Input value of SEED = 0.\n" );
    exit ( 1 );
  }
//
//  Update SEED.
//
  k = *seed / 127773;

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

  if ( *seed < 0 )
  {
    *seed = *seed + i4_huge;
  }
//
//  Convert SEED to a real number in [0,1].
//
  value = ( float ) ( *seed ) * 4.656612875E-10;
//
//  Scale to a real number in [A,B].
//
  value = a + ( b - a ) * value;

  return value;
}