[PATCH] Planner - change timestep to 2 seconds

[Steve Butler]

On 06/21/2015 04:40 PM, Rick Walsh wrote:
> Steve,
>
> On 22 June 2015 at 08:48, Steve Butler <kg7je at comcast.net 
> <mailto:kg7je at comcast.net>> wrote:
>
>     On 06/21/2015 03:23 PM, Rick Walsh wrote:
>>
>>     On 22 Jun 2015 8:16 am, "Steve Butler" <kg7je at comcast.net
>>     <mailto:kg7je at comcast.net>> wrote:
>>     >
>>     > On 06/20/2015 06:25 PM, Rick Walsh wrote:On 21 Jun 2015 11:19
>>     am, "Dirk Hohndel" <dirk at hohndel.org <mailto:dirk at hohndel.org>>
>>     wrote:
>>     >> >On Sat, Jun 20, 2015 at 11:17:28AM +1000, Rick Walsh wrote:
>>     >> > > But what about me?  I like SI units and whole decimals. 
>>     Don't worry, 2 s
>>     >> > > timesteps fit nicely when using 10 m/s ascent rate (18 s
>>     between stops).
>>
>     snip
>>
>>     > Also my DC records every 10s.  One of the DCs i'm looking at does 5s intervals.
>>     >
>>     > How would this work comparing the pre-dive plan with the
>>     post-dive profile?
>>     >
>>
>>     The change has nothing to do with setting or limiting an ascent
>>     rate. Currently the ascent to the next stop is done in 3 second
>>     increments. If you ascend at 30ft/min (Subsurface default, which
>>     matches most DCs) it should take 20s to ascend 10ft. But in 3s
>>     increments it is bumped out to 21s. No huge issue but it makes
>>     the calculated plan have some odd runtimes.
>>
>>
>     So that would be 10 calculations (one every 2s) between stops.  If
>     you slid the other way and went every 4s then its 5 calculations
>     up to the next stop.  Any concerns with snappiness (performance)
>     on slower machines?
>
>
> I have an 8 year old laptop, and calculations appear immediate, so I 
> don't think it's too intensive.  Changing from 3s to 2s means we do 10 
> calculations rather than 7, which isn't that dramatic.  Changing to 4s 
> is ok for a 30ft (9m) /min ascent rate, but for 20ft (6m) /min ascent 
> (also common), a stop should take 30s but that becomes 32s. 5s is ok 
> for 20ft/min or 30ft/min but isn't good for 5 m/min or 10 m/min.
>
> You are right, it isn't all that efficient.  I tried setting it to the 
> time it takes to ascend to the next stop (do the ascent in one jump), 
> which I thought should work. And to quote a great of modern 
> philosophy, "60 percent of the time it worked every time".  
> Occasionally, it would just break a ceiling.
> R
>
To paraphrase another great thinker -- "Efficiency is over-rated."

Or, "To err is human.  To really mess things up you need a computer."
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