Yes Vincent, that sounds much better, Cheers, Nishan On Saturday, 4 October 2014 05:21:15 UTC-4, vdelecroix wrote: > > Hello, > > Is it better worded as follows? > > The issue: plot(h(x), 0, 4) plots the line y=x−2, not the multi-line > function defined by h. The reason? In the command plot(h(x), 0, 4), > first h(x) is evaluated: this means plugging the symbolic variable x > into the function h. The inequality "x < 2" evaluates to ``False`` and > hence ``h(x)`` evaluates to ``x - 2`` as it can be seen with > {{{ > sage: bool(x < 2) > False > sage: h(x) > x - 2 > }}} > > I also find misleading to have a Python argument (the x in "def > h(x):") and a symbolic variable (here "x") having the same name. At > least it should be mentioned. > > Vincent > > 2014-10-02 20:32 UTC+02:00, NahsiN <nishan.s...@gmail.com <javascript:>>: > > @slelievre I was just pointing out what I think is a typo. > > @slelievre You are right, the clause after the statement clarifies the > > situation. "When a symbolic equation is evaluated, as in the definition > of > > h, > > if it is not obviously true, then it returns False. Thus h(x) evaluates > to > > x-2, and this is the function that gets plotted" But I still feel the > whole > > > > thing can be worded slightly better and more concisely. The if clause is > > evaluated anyway when one calls h(x) so there is no point in saying "x<2 > is > > evaluated". > > On Thursday, 2 October 2014 13:42:25 UTC-4, slelievre wrote: > >> > >> > >> > >> Le mercredi 1 octobre 2014 22:06:50 UTC+2, NahsiN a écrit : > >>> > >>> Hello, I don't know where to post this so redirect me as needed. I > >>> believe I have found a typo in the sage tutorial. Under Sage Tutorial > >>> v6.3 > >>> >> A Guided Tour >> Some Common Issues with Functions we have the > lines > >>> def h(x): > >>> if x<2: > >>> return 0 > >>> else: > >>> return x-2 > >>> > >>> The issue: plot(h(x), 0, 4) plots the line y=x−2, not the multi-line > >>> function defined by h. The reason? In the command plot(h(x),0, 4), > first > >>> > >>> h(x) is evaluated: this means plugging x into the function h, *which > >>> means that **x<2** is evaluated*. > >>> > >>> I think the else clause is evaluated and not the if x<2 clause. > >>> Thanks, > >>> Nishan > >>> > >> > >> You can work around this as follows: > >> > >> plot(lambda x: h(x), 0, 4) > >> > >> > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "sage-support" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to sage-support...@googlegroups.com <javascript:>. > > To post to this group, send email to sage-s...@googlegroups.com > <javascript:>. > > Visit this group at http://groups.google.com/group/sage-support. > > For more options, visit https://groups.google.com/d/optout. > > >
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