Hi John,

there's no dumb questions, maybe badly researched ones, and you
definitely don't have the habit of posting the latter, so: Good
question!

It all boils down to this line in gnuradio/gr-
qtgui/lib/numberdisplayform.cc:

      d_text_box[i]->setText(QString("%1 %2").arg(f, 4, ' ').\
                             arg(QString(d_unit[i].c_str())));

in which the current value `f` is displayed with four digits after the
decimal dot.

I'd agree this is probably not what's desirable in any application.

Now, this can be changed; for example, we could add a way to set the
number of digits variably instead of to 4. However, that'll be a source
code and API change, so it'll require recompilation of GNU Radio and
relinking of everything that use gr-qtgui. Does that help you?

Best regards,
Marcus

On Mon, 2018-03-05 at 16:36 -0500, John Ackermann N8UR wrote:
> I hate to put such a dumb question to the list, but I'm going nuts 
> trying to do something that ought to be simple.
> 
> I am using a QT Number Sink to display dB values in float format.  It is 
> showing many more decimal places than have any meaning.  I'd like to 
> round the display to one or two decimal places.
> 
> I tried making an embedded python block to do the rounding and finally 
> succeeded (it was a long and painful process, and frankly I don't 
> understand why I had to do what I did to get it to work), but the number 
> sink is still printing all the extra decimal places, they're just now 
> set to zero.
> 
> Is there any trick to round or even just truncate the number of decimal 
> places shown in the QT Number Sink?
> 
> Thanks,
> John
> 
> _______________________________________________
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> Discuss-gnuradio@gnu.org
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