Re: Why does one have to loop over the dispersion points? -- May 05, 2014 - 18:46

The reason why I ask, is that I am afraid that this for loop slows
everything down.

What do you think?

2014-05-05 18:41 GMT+02:00 Edward d'Auvergne <edward@xxxxxxxxxxxxx>:
> This is not Python specific though :)  As far as I know, C uses
> pass-by-value for arguments, unless they are arrays or other funky
> objects/functions/etc..  This is the same behaviour as Python.
> Pass-by-reference and pass-by-value is something that needs to be
> mastered in all languages, whether or not you have pointers to play
> with.
>
> Regards,
>
> Edward
>
>
>
> On 5 May 2014 18:30, Troels Emtekær Linnet <tlinnet@xxxxxxxxxxxxx> wrote:
> > This reminds me:
> >
> > http://combichem.blogspot.dk/2013/08/you-know-what-really-grinds-my-gears-in.html
> >
> > 2014-05-05 17:52 GMT+02:00 Edward d'Auvergne <edward@xxxxxxxxxxxxx>:
> > > Hi,
> > >
> > > This is an important difference.  In the first case (back_calc[i] =
> > > Minty[i]), what is happening is that your are copying the data into a
> > > pre-existing structure.  In the second case (back_calc = Minty), the
> > > existing back_calc structure will be overwritten.  Therefore the
> > > back_calc structure in the calling code will be modified in the first
> > > case but not the second.  Here is some demo code:
> > >
> > > def mod1(x):
> > >     x[0] = 1
> > >
> > > def mod2(x):
> > >     x = [3, 2]
> > >
> > > x = [0, 2]
> > > print(x)
> > > mod1(x)
> > > print(x)
> > > mod2(x)
> > > print(x)
> > >
> > > I don't know of a way around this.
> > >
> > > Regards,
> > >
> > > Edward
> > >
> > >
> > > On 5 May 2014 17:42, Troels Emtekær Linnet <tlinnet@xxxxxxxxxxxxx> wrote:
> > > > Hi Edward.
> > > >
> > > > In the library function of b14.py, i am looping over
> > > > the dispersion points to put in the data.
> > > >
> > > >     for i in range(num_points):
> > > >
> > > >         # The full formula.
> > > >         back_calc[i] = Minty[i]
> > > >
> > > > Why can I not just set:
> > > > back_calc = Minty
> > > >
> > > > _______________________________________________
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> > > >
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