proc ieee754 { value } {
 # covert value to double precision IEEE754 number
 if {$value > 0} {
  set sign 0
 } else {
  set sign 1
  set value [expr {-1. * $value}]
 }

 # If the following math fails, then it's because of the logarithm. That
means that value is indistinguishable from zero
 if {[catch {
  set exponent [expr {int(floor(log($value)/0.69314718055994529))+1023}]
  set fraction [expr {($value/pow(2.,double($exponent-1023)))-1.}]
 }]} {
  set exponent 0
  set fraction 0.0
 } else {
  # round off too-small values to zero, throw error for too-large values
  if {$exponent < 0} {
   set exponent 0
   set fraction 0.0
  } elseif {$exponent > 2047} {
   error "value $value outside legal range for a float"
  }
 }

 set fraction [expr {$fraction * 16.}]
 set f1f      [expr {floor($fraction)}]

 set fraction [expr {($fraction - $f1f) * 256.}]
 set f2f      [expr {floor($fraction)}]

 set fraction [expr {($fraction - $f2f) * 256.}]
 set f3f      [expr {floor($fraction)}]

 set fraction [expr {($fraction - $f3f) * 256.}]
 set f4f      [expr {floor($fraction)}]

 set fraction [expr {($fraction - $f4f) * 256.}]
 set f5f      [expr {floor($fraction)}]

 set fraction [expr {($fraction - $f5f) * 256.}]
 set f6f      [expr {floor($fraction)}]

 set fraction [expr {($fraction - $f6f) * 256.}]
 set f7f      [expr {floor($fraction)}]

 for {set i 1} {$i <= 7} {incr i} {
  set var "f$i"
  append var "f"
  set f$i [expr {int([set $var])}]
 }

 set se1 [expr {($sign ? 128 : 0) | ($exponent >> 4)}]
 set e2f1 [expr {(($exponent & 15) * 16) | $f1}]

 set bytes [binary format cccccccc $f7 $f6 $f5 $f4 $f3 $f2 $e2f1 $se1]

 return $bytes