# [Maxima] wrong graph

Stavros Macrakis macrakis at alum.mit.edu
Tue Jan 3 12:35:41 CST 2012

```Luigi,

I tried your code, and got the following graph, which looks correct to me
-- is that the graph you get?

Though of course sqrt(-2) is not real, sqrt(-2)/sqrt(-1) is real.  There is
no good way to tell Maxima to do strictly real arithmetic, such that (e.g.)
sqrt(-1)/sqrt(-1) gives Undefined instead of 1.  Is that what you want?

-s

PS Please keep the Maxima mailing list CC'ed on discussions.
[image: image.png]
On Tue, Jan 3, 2012 at 02:09, Luigi Marino <luigi_marino2 at alice.it> wrote:

> **
> Hi Stravos
> Maxima works in complex mode.
> Look at my file.
> I use the last Maxima release 5.21
> Best.
> Luigi
>
> ----- Original Message -----
> *From:* Stavros Macrakis <macrakis at alum.mit.edu>
> *To:* Luigi Marino <luigi_marino2 at alice.it>
> *Cc:* maxima at math.utexas.edu
> *Sent:* Tuesday, January 03, 2012 12:27 AM
> *Subject:* Re: [Maxima] wrong graph
>
> For x>0 and x< -1, the result is real:
>
>  makelist(x*sqrt(x)/sqrt(1+x),x,[-1.5,-.5,.5,1.5]);
> (%o69)         [- 2.598076211353316, - 0.5 %i, 0.28867513459481,
> 1.161895003862225]
>
> For x>-1 and x< 0, the result is imaginary, and is not plotted, so there
> is a gap in the plot.
>
> Is that what you are referring to?
>
>              -s
>
> PS For reports like this, please include the version number of Maxima, the
> exact command you used to generate the result you think is incorrect, and
> why you think it is incorrect.
>
>
> On Sun, Jan 1, 2012 at 09:14, Luigi Marino <luigi_marino2 at alice.it> wrote:
>
>> **
>> Maxima for a function with rational exponent
>> plots not real parts.
>>
>> Example in the function:
>>
>> x*sqrt(x)/sqrt(1+x)
>> or x^(3/2)/sqrt(1+x)
>>
>> the left part of the plot
>> is not real ( x>0 for sqrt).
>>
>> Best wishes and Happy New Year
>> Luigi Marino
>>
>>
>> _______________________________________________
>> Maxima mailing list
>> Maxima at math.utexas.edu
>> http://www.math.utexas.edu/mailman/listinfo/maxima
>>
>>
>
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