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Sage unable to make sense of Maxima expression when solving a system involving square roots #24800

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sagetrac-tmonteil mannequin opened this issue Feb 20, 2018 · 2 comments

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@sagetrac-tmonteil
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sagetrac-tmonteil mannequin commented Feb 20, 2018

As reported on his ask question, trying to solve the following equation leads to an error:

var('r2 si co r12 r22 r32 d32')
eq1 = r12==r2*d32*(1-si*(co+sqrt(3*(1-co*co)))/2)/2
eq2 = r22==r2*d32*(1-si*(co-sqrt(3*(1-co*co)))/2)/2
eq3 = r32==r2*d32*(1+si*co)/2
solve([eq1,eq2,eq3],r2,si,co)

leads to

TypeError: unable to make sense of Maxima expression '[if((-pi/2<parg(-((3*_SAGE_VAR_r22-3*_SAGE_VAR_r12)*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(2*_SAGE_VAR_r32^2+((-2*_SAGE_VAR_r22)-2*_SAGE_VAR_r12)*_SAGE_VAR_r32+2*_SAGE_VAR_r22^2-2*_SAGE_VAR_r12*_SAGE_VAR_r22+2*_SAGE_VAR_r12^2)))and(parg(-((3*_SAGE_VAR_r22-3*_SAGE_VAR_r12)*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(2*_SAGE_VAR_r32^2+((-2*_SAGE_VAR_r22)-2*_SAGE_VAR_r12)*_SAGE_VAR_r32+2*_SAGE_VAR_r22^2-2*_SAGE_VAR_r12*_SAGE_VAR_r22+2*_SAGE_VAR_r12^2))<==pi/2),[_SAGE_VAR_co==-((2*_SAGE_VAR_r32-_SAGE_VAR_r22-_SAGE_VAR_r12)*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(2*_SAGE_VAR_r32^2+((-2*_SAGE_VAR_r22)-2*_SAGE_VAR_r12)*_SAGE_VAR_r32+2*_SAGE_VAR_r22^2-2*_SAGE_VAR_r12*_SAGE_VAR_r22+2*_SAGE_VAR_r12^2),_SAGE_VAR_r2==(2*_SAGE_VAR_r32+2*_SAGE_VAR_r22+2*_SAGE_VAR_r12)/(3*_SAGE_VAR_d32),_SAGE_VAR_si==-(2*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(_SAGE_VAR_r32+_SAGE_VAR_r22+_SAGE_VAR_r12)],union()),if((-pi/2<parg(((3*_SAGE_VAR_r22-3*_SAGE_VAR_r12)*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(2*_SAGE_VAR_r32^2+((-2*_SAGE_VAR_r22)-2*_SAGE_VAR_r12)*_SAGE_VAR_r32+2*_SAGE_VAR_r22^2-2*_SAGE_VAR_r12*_SAGE_VAR_r22+2*_SAGE_VAR_r12^2)))and(parg(((3*_SAGE_VAR_r22-3*_SAGE_VAR_r12)*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(2*_SAGE_VAR_r32^2+((-2*_SAGE_VAR_r22)-2*_SAGE_VAR_r12)*_SAGE_VAR_r32+2*_SAGE_VAR_r22^2-2*_SAGE_VAR_r12*_SAGE_VAR_r22+2*_SAGE_VAR_r12^2))<==pi/2),[_SAGE_VAR_co==((2*_SAGE_VAR_r32-_SAGE_VAR_r22-_SAGE_VAR_r12)*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(2*_SAGE_VAR_r32^2+((-2*_SAGE_VAR_r22)-2*_SAGE_VAR_r12)*_SAGE_VAR_r32+2*_SAGE_VAR_r22^2-2*_SAGE_VAR_r12*_SAGE_VAR_r22+2*_SAGE_VAR_r12^2),_SAGE_VAR_r2==(2*_SAGE_VAR_r32+2*_SAGE_VAR_r22+2*_SAGE_VAR_r12)/(3*_SAGE_VAR_d32),_SAGE_VAR_si==(2*sqrt(_SAGE_VAR_r32^2+((-_SAGE_VAR_r22)-_SAGE_VAR_r12)*_SAGE_VAR_r32+_SAGE_VAR_r22^2-_SAGE_VAR_r12*_SAGE_VAR_r22+_SAGE_VAR_r12^2))/(_SAGE_VAR_r32+_SAGE_VAR_r22+_SAGE_VAR_r12)],union())]' in Sage

I am not familiar with the interface between Sage and Maxima, but it seems that Sage is not able to handle the conditional answers (if ... and ...)

Component: symbolics

Issue created by migration from https://trac.sagemath.org/ticket/24800

@sagetrac-tmonteil sagetrac-tmonteil mannequin added this to the sage-8.2 milestone Feb 20, 2018
@rwst
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rwst commented Feb 23, 2018

comment:1

Duplicate of #13773. Unfortunately SymPy takes forever in this case.

@rwst rwst removed this from the sage-8.2 milestone Feb 24, 2018
@videlec
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videlec commented May 18, 2018

comment:4

closing positively reviewed duplicates

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