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Dec 11, 2009, 7:46:31 AM12/11/09

to Sage devel

Hello everybody !!!

I just met what I believe is a Sage bug if not a misuse of it from my

behalf, and I have no idea of how to create the corresponding ticket,

symbolics not being my field in any way. besides, I produced this bug

using the sage version with is installed in sage.math ( recompiling

the new version at the moment, I do not have any Sage available ). It

may be solved already but here it is anyway :

sage: var('delta k')

sage: m1=2*delta**2 + 2**2*delta*k

sage: n=delta*k+2

sage: m2=(2*delta)**2+(k-1)*4

sage: m=(delta+delta*k-(delta-1))

sage: ((m1/n)-(m2/n)).expand().simplify()

I will find another way to compute this, I was just too lazy to use

paper, so I am not blocked in any way, but this remains a bug that may

be created by a more clever use of Sage :-)

Thankkkkks !!! :-)

Nathann

I just met what I believe is a Sage bug if not a misuse of it from my

behalf, and I have no idea of how to create the corresponding ticket,

symbolics not being my field in any way. besides, I produced this bug

using the sage version with is installed in sage.math ( recompiling

the new version at the moment, I do not have any Sage available ). It

may be solved already but here it is anyway :

sage: var('delta k')

sage: m1=2*delta**2 + 2**2*delta*k

sage: n=delta*k+2

sage: m2=(2*delta)**2+(k-1)*4

sage: m=(delta+delta*k-(delta-1))

sage: ((m1/n)-(m2/n)).expand().simplify()

I will find another way to compute this, I was just too lazy to use

paper, so I am not blocked in any way, but this remains a bug that may

be created by a more clever use of Sage :-)

Thankkkkks !!! :-)

Nathann

Dec 11, 2009, 9:19:37 AM12/11/09

to sage-...@googlegroups.com

Hi Nathann,

On Fri, 11 Dec 2009 13:46:31 +0100

Nathann Cohen <nathan...@gmail.com> wrote:

> Hello everybody !!!

>

> I just met what I believe is a Sage bug if not a misuse of it from my

> behalf, and I have no idea of how to create the corresponding ticket,

> symbolics not being my field in any way. besides, I produced this bug

> using the sage version with is installed in sage.math ( recompiling

> the new version at the moment, I do not have any Sage available ). It

> may be solved already but here it is anyway :

>

>

> sage: var('delta k')

> sage: m1=2*delta**2 + 2**2*delta*k

> sage: n=delta*k+2

> sage: m2=(2*delta)**2+(k-1)*4

> sage: m=(delta+delta*k-(delta-1))

> sage: ((m1/n)-(m2/n)).expand().simplify()

On 4.3.rc0, I get this:

TypeError: unsupported operand parent(s) for '*': 'Symbolic Ring' and

'<class 'sage.functions.generalized.FunctionDiracDelta'>'

Is this same problem you're seeing?

The Maxima interface seems to give precedence to the global function

dictionary instead of the local variables when converting Maxima output

back to Sage expressions.

sage: dirac_delta(x)

dirac_delta(x)

sage: maxima(dirac_delta(x))

delta(x)

I opened a ticket for this:

http://trac.sagemath.org/sage_trac/ticket/7661

You can work around the problem by avoiding the variable name delta:

sage: var('d k')

(d, k)

sage: m1=2*d**2 + 2**2*d*k

sage: n=d*k+2

sage: m2=(2*d)**2+(k-1)*4

sage: sage: m=(d+d*k-(d-1))

sage: m=(d+d*k-(d-1))

sage: ((m1/n)-(m2/n)).expand().simplify()

-2*d^2/(d*k + 2) + 4*d*k/(d*k + 2) - 4*k/(d*k + 2) + 4/(d*k + 2)

Cheers,

Burcin

On Fri, 11 Dec 2009 13:46:31 +0100

Nathann Cohen <nathan...@gmail.com> wrote:

> Hello everybody !!!

>

> I just met what I believe is a Sage bug if not a misuse of it from my

> behalf, and I have no idea of how to create the corresponding ticket,

> symbolics not being my field in any way. besides, I produced this bug

> using the sage version with is installed in sage.math ( recompiling

> the new version at the moment, I do not have any Sage available ). It

> may be solved already but here it is anyway :

>

>

> sage: var('delta k')

> sage: m1=2*delta**2 + 2**2*delta*k

> sage: n=delta*k+2

> sage: m2=(2*delta)**2+(k-1)*4

> sage: m=(delta+delta*k-(delta-1))

> sage: ((m1/n)-(m2/n)).expand().simplify()

TypeError: unsupported operand parent(s) for '*': 'Symbolic Ring' and

'<class 'sage.functions.generalized.FunctionDiracDelta'>'

Is this same problem you're seeing?

The Maxima interface seems to give precedence to the global function

dictionary instead of the local variables when converting Maxima output

back to Sage expressions.

sage: dirac_delta(x)

dirac_delta(x)

sage: maxima(dirac_delta(x))

delta(x)

I opened a ticket for this:

http://trac.sagemath.org/sage_trac/ticket/7661

You can work around the problem by avoiding the variable name delta:

sage: var('d k')

(d, k)

sage: m1=2*d**2 + 2**2*d*k

sage: n=d*k+2

sage: m2=(2*d)**2+(k-1)*4

sage: sage: m=(d+d*k-(d-1))

sage: m=(d+d*k-(d-1))

sage: ((m1/n)-(m2/n)).expand().simplify()

-2*d^2/(d*k + 2) + 4*d*k/(d*k + 2) - 4*k/(d*k + 2) + 4/(d*k + 2)

Cheers,

Burcin

Dec 11, 2009, 9:22:38 AM12/11/09

to sage-...@googlegroups.com

A protected name... I see :-)

Thank you !!!

Nathann

Thank you !!!

Nathann

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