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#59 make install sets the wrong shell variable in the axiom script  ← ↑ →  #60 bugs duplicate functions exists. optimizer complains during rebuild

#6 integration result Gamma not TeXed correctly
  
last edited 10 years ago by test1

Edit detail for #6 integration result Gamma not TeXed correctly revision 6 of 7
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Editor: kratt6
Time: 2007/12/24 02:42:36 GMT-8
Note: 
added:

From kratt6 Mon Dec 24 02:42:36 -0800 2007
From: kratt6
Date: Mon, 24 Dec 2007 02:42:36 -0800
Subject: 
Message-ID: <20071224024236-0800@axiom-wiki.newsynthesis.org>

fixed in FriCAS

Submitted by : (unknown) at: 2007-11-17T23:01:10-08:00 (17 years ago)
Name :
Axiom Version :
Category : Severity : Status :
Optional subject :  
Optional comment : 

integrate((x^2)*(%e^(-x^2)),x=0..%plusInfinity) does not give
sqrt(%pi)/4.





(new) --Bob McElrath,  Wed, 22 Dec 2004 21:57:46 -0600 reply
anonymous [mathaction@axiom-developer.org] wrote:

integrate((x^2)*(%e^(-x^2)),x=0..%plusInfinity) does not give
sqrt(%pi)/4.


The answer it gives is correct (unless there is a new bug introduced
that is not on my axiom 0.20040831-1).  The gamma function has sqrt(pi)
for half-integer values.


fricas
integrate(x^2*(exp(-x^2)), x=0..%plusInfinity)

\begin{equation}
\label{eq1}{\sqrt{\pi}}\over 4\end{equation}

Type: Union(f1: OrderedCompletion?(Expression(Integer)),...)


fricas
Gamma(3/2)/2::Float

\begin{equation}
\label{eq2}{0.5}\ {\Gamma \left({1.5}\right)}\end{equation}

Type: Expression(Float)


fricas
sqrt(%pi)/4::Float

\begin{equation}
\label{eq3}0.4431134627_2637900682\end{equation}

Type: Expression(Float)


What I don't understand is why the integration result is so hard to
convert to a Float.  Appending ::Float to the integrate() command
fails.  Why?  If I type Gamma(3/2)/2 by hand it has no problem.


(new) --Bob McElrath?,  Wed, 22 Dec 2004 22:13:50 -0600 reply
Actually the text output is:

          _ 3
         | (-)
            2
   (28)  -----
           2
                    Type: Union(f1: OrderedCompletion Expression Integer,...)





which I assume is the Gamma function, but the tex is converted improperly:

    {{|{\overline {\ }}} 
    \left(
    {{3 \over 2}} 
    \right)}
    \over 2 
    \leqno(29)





i.e. clearly does not contain \Gamma.


{|{\overline {\ } == Gamma? --Bill Page,  Thu, 23 Dec 2004 01:32:23 -0600 reply
It is possible to convert this peculiar monogram to \Gamma for
display but I think the problem is more fundamental. Clearly AXIOM
does not have a consistent and complete representation of the Gamma
function. I think integrate should at least return a Gamma that can
be converted to Float or something of type Expression Integer like
sqrt(%pi)/4. But it seems that the current Gamma function always
agressively returns a DoubleFloat? value. This doesn't seem very
useful to me for symbolic computations.


{|{\overline {\ } == Gamma? --Bob McElrath?,  Thu, 23 Dec 2004 01:42:39 -0600 reply
Bill, What is the type that is returned there?  How can I get axiom to
print the entire type rather than ...?


I think therein lies the problem.  Note that

fricas
integrate(x^2*(exp(-x^2)), x=0..%plusInfinity)::InputForm

\begin{equation}
\label{eq4}\left(/ \ {\left(^\ {\left(pi \right)}\ {\left(/ \  1 \  2 \right)}\right)}\  4 \right)\end{equation}

Type: InputForm?


seems correct.


P.S. IssueTracker? + axiom rules.  Having axiom right here is so
powerful...  I will have to pay more attention to IssueTracker?.  I was
half thinking to strip it when (if) I fork zwiki.  Right now
IssueTracker? is a big hack that can't be uninstalled...


this is not a math bug, only the output is not as nice as it could be --kratt6,  Wed, 19 Jan 2005 08:34:21 -0600 reply
Category: Axiom Mathematics => Axiom User Interface 
Severity: normal => minor 


I think this is a math bug! --Bill Page,  Wed, 19 Jan 2005 08:54:51 -0600 reply
I disagree. There is something fundamentally wrong here. The result of

fricas
integrate(x^2*(exp(-x^2)), x=0..%plusInfinity)

\begin{equation}
\label{eq5}{\sqrt{\pi}}\over 4\end{equation}

Type: Union(f1: OrderedCompletion?(Expression(Integer)),...)


Not only prints oddly without conversion to proper LaTeX? but also it
is not actually recognized "mathematically" as Gamma().


Further, there is something wrong with the implementation of Gamma()
itself because it only works numerically and is of no use symbolically.
It seems like there are two separate Gamma functions. The one produced
by the integration is "symbolic" but does not seem to be connected to
any appropriate logic.


this is not a mathbug, only the output is not as nice as it could be --Bill Page,  Wed, 19 Jan 2005 09:20:12 -0600 reply


Category: Axiom Mathematics => Axiom User Interface 
Severity: normal => minor 

    :)




This shows where your priorities are Martin! But, thanks.


Some User Interface issue is involved here, but I don't
think that it is quite correct to classify it this way.
The issue is really what symbollic computations are
possible in Axiom involving Gamma? I would say that this
is more of a deficiency in the mathmatics.


... --kratt6,  Thu, 20 Dec 2007 11:33:13 -0800 reply
Name: #6 wrong integration result => #6 integration result Gamma not TeXed correctly 


... --kratt6,  Sun, 23 Dec 2007 10:32:06 -0800 reply
Here is a simple patch:

  diff -c /home/martin/fricas/src/algebra/op.spad.pamphlet\~ /home/martin/fricas/src/algebra/op.spad.pamphlet
  *** /home/martin/fricas/src/algebra/op.spad.pamphlet~ 2007-12-23 18:14:48.000000000 +0100
  --- /home/martin/fricas/src/algebra/op.spad.pamphlet  2007-12-23 19:14:41.000000000 +0100
  ***************
  *** 443,449 ****
        dpi l    == "%pi"::Symbol::O
        dfact x  == postfix("!"::Symbol::O, (ATOM(x)$Lisp => x; paren x))
        dquote l == prefix(quote(first(l)::O), rest l)
  !     dgamma l == prefix(hconcat(super("|"::Symbol::O, "-"::Symbol::O)), l)
        setDummyVar(op, n) == setProperty(op, DUMMYVAR, n pretend None)

        dexp x ==
  --- 443,468 ----
        dpi l    == "%pi"::Symbol::O
        dfact x  == postfix("!"::Symbol::O, (ATOM(x)$Lisp => x; paren x))
        dquote l == prefix(quote(first(l)::O), rest l)
  !     dgamma l == prefix(super("|"::Symbol::O, "-"::Symbol::O), l)
  ! @
  ! 
  ! It is certainly an abuse of [[OutputForm]] to produce a Gamma as done above.
  ! Originally, it was even worse:
  ! \begin{verbatim}
  !     dgamma l == prefix(hconcat("|"::Symbol::O, overbar(" "::Symbol::O)), l)
  ! \end{verbatim}
  ! which was TeXed to
  ! $$
  ! {|{\overline {\ }}} 
  ! \left(
  ! {x} 
  ! \right).
  ! $$
  ! 
  ! The right thing would be to introduce Greek letters in [[OutputForm]], but that
  ! should be coordinated with the new mathml package.
  ! 
  ! <<package COMMONOP CommonOperators>>=
        setDummyVar(op, n) == setProperty(op, DUMMYVAR, n pretend None)

        dexp x ==





Warning: Gamma looks slightly different in ASCII then.  A better patch is discussed on the FriCAS? list, 23.12.2007


Martin


... --kratt6,  Sun, 23 Dec 2007 10:47:37 -0800 reply
Status: open => fix proposed 


patch attached.  Observation by Bill Page transferred to new report #408


... --kratt6,  Mon, 24 Dec 2007 02:42:36 -0800 reply
fixed in FriCAS?
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[1] [2] [3]
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<to be read again> 
                   \ 
l.128 \label{eq4}\left(/ \ {\left(^\ 
                                     {\left(pi \right)}\ {\left(/ \  1 \  2 ...
 Missing } inserted.
<inserted text> 
                }
l.128 ...ight)}\ {\left(/ \  1 \  2 \right)}\right
                                                  )}\  4 \right)\end{equatio...




[4] [5] [6] [7] (/usr/share/texmf-texlive/tex/latex/base/t1cmtt.fd)


LaTeX Warning: Characters dropped after `\end{verbatim}' on input line 135.


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