Re: Infinit loop in /free

[Hans Boldt <boldt@xxxxxxxxxx>]

Steve Richter wrote:

> well I just had to test this ( comparing a count to a 31 digit packed
> decimal hival number seems a bit wasteful ) ...
>
> the following million iteration loop runs for 63 milliseconds on a 170/2386
> ( 400+ cpw ):
> ...
>
> and this do *hival version runs for 390 milliseconds
> ...    
>
> -Steve

So this means that in a loop that does nothing, a DOW loop is preferable 
to DO *HIVAL. In practice, most loops do a bit more than that, and so 
the difference in loop overhead is usually swamped by the operations 
within the loop.

But the comparison itself is flawed. The former uses a 10I0 variable as 
loop index, the latter uses an implicitly defined decimal variable with 
a precision of 31 digits. To make the comparison fair, define IX as 31P0 
in the first program.

Out of curiosity, let's examine this result further. For the latter 
program, "DO *HIVAL" runs about 3 million iterations per second. If we 
let the program run for *HIVAL iterations, how long will we have to wait 
for the loop to end? My calculations show we'll have to wait, oh, about 
a hundred million billion years. ;-)

Cheers! Hans