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solving equation involving absolute values

asked 2015-03-24 06:13:43 +0100

sundar gravatar image


I am newbie to sagemath. I have windows 8 and sage version is 6.4.1. I am running it inside virtualbox. I was reading some thing about solving equations on sage website at

At one point author is trying to demonstrate the use of optional keywords for the "solve" He is solving equation

solve(abs(1-abs(1-x)) == 10, x)

When evaluated this gives

[abs(abs(x - 1) - 1) == 10]

But when the input is modified a little as

solve(abs(1-abs(1-x)) == 10, x, to_poly_solve=True)

sage gives correct result as [x == -10, x == 12]

So why does it not work in the first case ? I didn't understand this use of keyword to_poly_solve.

I tried to post this question on sage-support but for some reason my posted question doesn't seem to appear there.

Please help sundar

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answered 2015-03-24 08:08:14 +0100

rws gravatar image

Sage uses other programs for many of its functionality. In symbolic calculus Sage relies on Maxima for doing integrals, ODEs, limits, equations, simplifications and other things. Equation solving uses Maxima's core but this has limited functionality. Maxima itself in turn makes use of additional packages to augment its abilities.

If you type:

sage: solve??

you see among other things:

-  ``to_poly_solve`` - bool (default: False) or string; use
   Maxima's ``to_poly_solver`` package to search for more possible
   solutions, but possibly encounter approximate solutions.
   This keyword is incompatible with ``multiplicities=True``
   and is not used when solving inequalities. Setting ``to_poly_solve``
   to 'force' (string) omits Maxima's solve command (useful when
   some solutions of trigonometric equations are lost).
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sundar gravatar imagesundar ( 2015-03-24 08:33:46 +0100 )edit

If this answers your question, please do click the "check mark" to accept the answer so that visitors coming to this question know it has been answered :)

kcrisman gravatar imagekcrisman ( 2015-03-24 14:51:40 +0100 )edit

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Asked: 2015-03-24 06:13:43 +0100

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Last updated: Mar 24 '15