Integration error

Ajit Kumar
2013-05-03
2013-05-18
  • Ajit Kumar

    Ajit Kumar - 2013-05-03

    The following integration command gives output as -8 where as the answer should be 8.

    integrate(sqrt(8 - 8*cos(2*t)), t, 0, %pi);

    Can't think of why.

     
  • Albrecht Mueller

    I could reproduce the problem and think that this is an error. Created ticket #2575.

     
  • Aleksas

    Aleksas - 2013-05-09

    (%i1) S:'integrate(sqrt(8 - 8cos(2t)), t, 0, %pi);
    (%o1) integrate(sqrt(8-8cos(2t)),t,0,%pi)
    (%i2) ev(%, nouns);
    (%o2) -8
    This is maxima bug. Next we solve step-by-step.

    (%i3) trigexpand(S);
    (%o3) integrate(sqrt(8-8(cos(t)^2-sin(t)^2)),t,0,%pi)
    (%i4) S1:trigsimp(%);
    (%o4) 4
    integrate(abs(sin(t)),t,0,%pi)
    (%i5) assume(sin(t)>0)$
    (%i6) ev(S1, nouns);
    (%o6) 8

    best

    Aleksas D

     
  • Ajit Kumar

    Ajit Kumar - 2013-05-18

    Thanks

     

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