On Thu, 25 Mar 2004, Ulrich Dirr wrote:

 > On occasion I need to trace TeX's page building via \tracingpages=2.
 > Assume you have a \textheight of 39 \baselineskip + \topskip, and one
 > \baselineskip is 13bp. Then \textheight is 507bp+10pt. Using the above
 > definition for bp this should be 518.90125pt. But when tracing the
 > pages I always got a pagegoal of 518.90073pt resulting often in
 > underfull \vbox messages (I've hopefully eliminated all uncontrolled
 > stretching and shrinking of vertical material in my setup).
 > Maybe someone could explain this behavior to me?

Simple rounding errors. Internally everything is computed in scaled points
= 1/65536pt. So, your \baselineskip is

  13*7227*65536 / 7200 = 855162

The textheight is then

  39*855162 + 10*65536 = 34006678

In points this is

  34006678/65536 = 518.90073

 Rainer Schöpf