and how does one use [lpi] in a mac? 2015-01-29 15:47 GMT-02:00 Martin Peach <[email protected]>:
> Here's a patch using pdlua that shows the value of pi in various ways. I > get 48 decimal places in a symbol. > > Martin > > On Thu, Jan 29, 2015 at 12:36 PM, Alexandre Torres Porres < > [email protected]> wrote: > >> > more that 7 digit but less than 8 digits >> ... >> > so, 4/3 =! 1.33333 >> > but 4/3 == 1.33333333 (8 "3") >> >> I don't get it. More than 7 decimal digits but less than 8 decimal >> digits? How does that work? In practice, is it 7 or 8? >> >> In the example we see that 4/3 == 1.33333333 (8 "3") - so it's 8 decimal >> digits... >> >> I have a work around using expr. Just put the number in parenthesis. >> >> Try [expr 4./3 == (1.33333333)] (8 "3") >> >> but the thing is that this is also true - [expr 4./3 == (1.3333333)] - also >> equal to 7 "3" >> >> cheers >> >> 2015-01-29 14:58 GMT-02:00 Cyrille Henry <[email protected]>: >> >> hello, >>> >>> ok, claude was faster to answer, but since i already write my mail, i >>> send it anyway... >>> >>> >>> pd internal resolution is float32. >>> (i.e, 23 bit, so a bit less than 17 millions, i.e more that 7 digit but >>> less than 8 digits) >>> pd graphical representation is 6 digits >>> >>> so, 4/3 =! 1.33333 but 4/3 == 1.33333333 (8 "3") >>> even if both are represented with the same number of 3... >>> this is a generic problem of computer float. >>> >>> the only odd thing concerning pd is that number are also saved with 6 >>> digit. >>> (so precision can be lost when a patch is saved) >>> >>> try the attachment patch. >>> then save the patch, and open it back, and see that precision is lost. >>> (I have to modifies the patch as text file to have this behaviors, but >>> you can also have the save precision when creating an object... until you >>> save/load the patch) >>> >>> you can also have a look on the top right of the patch: a weird effect >>> of float precision... >>> >>> cheers >>> c >>> >>> Le 29/01/2015 17:17, Alexandre Torres Porres a écrit : >>> >>>> Well, thanks everyone. >>>> >>>> And now for some related issues. >>>> >>>> Pd can only represent up to 6 significant digits, so they say. For >>>> example, in a message, you can have a number with up to 5 decimal places, >>>> like: -5.29314e+12 >>>> >>>> but it does have a better internal resolution, if you compare 4 / 3 to >>>> 1.33333 you'll see 4 / 3 is higher ( try [expr 4./3 > 1.33333] and check). >>>> >>>> So, what's this internal resolution? And why can't you have the same >>>> resolution in a message? >>>> >>>> thanks >>>> >>>> 2015-01-28 16:06 GMT-02:00 Martin Peach <[email protected] <mailto: >>>> [email protected]>>: >>>> >>>> On Wed, Jan 28, 2015 at 12:00 PM, Cyrille Henry <[email protected] >>>> <mailto:[email protected]>> wrote: >>>> >>>> >>>> >>>> Le 28/01/2015 17:47, Alexandre Torres Porres a écrit : >>>> >>>> > it's a limitation of 32 bit float >>>> >>>> I thought so, but same happens when I use the new Pd >>>> Vanilla 64 bits... >>>> >>>> this mean that it's compiled for 64 bit CPU, not that float are >>>> store on 64 bits >>>> >>>> Also last time I checked, Pd saves floats by first printing them to >>>> 6 digit precision, so they have even less range than a 'float' type. >>>> You could use an object made with pdlua to manipulate large >>>> floating-point numbers, as there is no(?) limit to the size of a float in >>>> lua. >>>> >>>> Martin >>>> >>>> _______________________________________________ >>>> [email protected] <mailto:[email protected]> mailing list >>>> UNSUBSCRIBE and account-management -> http://lists.puredata.info/ >>>> listinfo/pd-list >>>> >>>> >>>> >> >
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