> Am 04.01.2018 um 11:13 schrieb Schaff, Frederik: > > Happy New Year!
> > And to you! (and everybody) > > > guess it is a problem with large integer (part) of the numbers? Is > > this only the visible behaviour or can it really distort the data and > > computations? In this case it wouldn’t matter, but in other cases it > > might… > > There are two separate issues here, the internal number representation and > the printed format. > > AFAIK in gretl basically everything is stored as a double precision float > (should > be 64 bit == 8 byte wide). It is a standard computer science thing that > floating > point numbers cannot exactly represent all integers, and in principle you also > have the possibility of overflow. In this (very old and universal) sense yes > in > principle it could affect the results. This is not usually a problem in > practice, > however. > > The limited number of digits/precision which is displayed is different from > that. There are some 'set' options for that for example, quoted from the > command ref: > > <doc> > - display_digits: an integer from 3 to 6, specifying the number of significant > digits to use when displaying regression coefficients and standard errors (the > default being 6). This setting can also be used to limit the number of digits > shown by the summary command; in this case the default (and also the > maximum) is 5, or 4 when the --simple option is given. > > - mwrite_g: on or off (the default). When writing a matrix to file as text, > gretl > by default uses scientific notation with 18-digit precision, hence ensuring > that > the stored values are a faithful representation of the numbers in memory. > When writing primary data with no more than 6 digits of precision it may be > preferable to use %g format for a more compact and human-readable file; > you can make this switch via set mwrite_g on. > </doc> > > In the "show values" (zeige Werte) window there is also a button number > format (Zahlenformat) where a different display can be chosen. > > hth, > sven That trick did it, thanks!. For the record, selecting “reformat” ( [cid:image001.png(a)01D38554.89894C60] ) and then show (e.g.) the 15 significant figures worked fine Frederik
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> Am 04.01.2018 um 11:13 schrieb Schaff, Frederik: > > Happy New Year! > > And to you! (and everybody) > > > guess it is a problem with large integer (part) of the numbers? Is > > this only the visible behaviour or can it really distort the data and > > computations? In this case it wouldn’t matter, but in other cases it > > might… > > There are two separate issues here, the internal number representation and > the printed format. > > AFAIK in gretl basically everything is stored as a double precision float (should > be 64 bit == 8 byte wide). It is a standard computer science thing that floating > point numbers cannot exactly represent all integers, and in principle you also > have the possibility of overflow. In this (very old and universal) sense yes in > principle it could affect the results. This is not usually a problem in practice, > however. > > The limited number of digits/precision which is displayed is different from > that. There are some 'set' options for that for example, quoted from the > command ref: > > <doc> > - display_digits: an integer from 3 to 6, specifying the number of significant > digits to use when displaying regression coefficients and standard errors (the > default being 6). This setting can also be used to limit the number of digits > shown by the summary command; in this case the default (and also the > maximum) is 5, or 4 when the --simple option is given. > > - mwrite_g: on or off (the default). When writing a matrix to file as text, gretl > by default uses scientific notation with 18-digit precision, hence ensuring that > the stored values are a faithful representation of the numbers in memory. > When writing primary data with no more than 6 digits of precision it may be > preferable to use %g format for a more compact and human-readable file; > you can make this switch via set mwrite_g on. > </doc> > > In the "show values" (zeige Werte) window there is also a button number > format (Zahlenformat) where a different display can be chosen. > > hth, > sven That trick did it, thanks!. For the record, selecting “reformat” (
Frederik |
