ode2 asks a question related to "ynew" without
defining ynew.
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(%i1) display2d:false$
(%i2) de : 'diff(y,x,2) + sin(y);
(%o2) 'diff(y,x,2)+sin(y)
(%i3) ode2(de,y,x);
Is sin(2*ynew)-2*%k1*sin(ynew) positive, negative, or zero?
p;
(%o3) [-('integrate(1/sqrt(cos(y)-%k1),y))/sqrt(2) = x+%k2,
('integrate(1/sqrt(cos(y)-%k1),y))/sqrt(2) = x+%k2]
(%i4) load('contrib_ode);
(%o4)
"C:/PROGRA~1/MAXIMA~3.1/share/maxima/5.18.1/share/contrib/diffequations/contrib_ode.mac"
(%i5) contrib_ode(de,y,x);
(%o5) false
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I realize that ode2 needs to know the sign of *something*, so I am glad to
take a stab at an answer, but this seems similar to nonsensical questions
from integrate.
Ted Woollett
Win XP, 5.18.1