#2787 gives wrong answer and asks redundant questions - integrals

None
open
nobody
None
5
2014-07-29
2014-07-22
dan hayes
No

wxMaxima version: 13.4.0
Maxima version: 5.31.1
Maxima build date: 2013-09-24 09:49:12
Host type: i686-pc-mingw32
Lisp implementation type: GNU Common Lisp (GCL)
Lisp implementation version: GCL 2.6.8

(assume(a>1/16,b>4*a,c>4*b),t:integrate(1/(a^2+b^2*k^2+c^2*k^4),k,-inf,inf));

Now it is obvious the integral is positive definite and not infinite. it asks is -b^2+2*a+1/8 pos,neg,or 0 and i answer negative and it comes out with WRONG answer of 0. Next:

(assume(a>0,a<1/16,b>1,c>4*b),t:integrate(1/(a^2+b^2*k^2+c^2*k^4),k,-inf,inf));

Now it asks the same ridiculous question again which has to be negative which is obvious negative from the given assumes Anyway i answer negative and again gives WRONG answer 0.

Next do:

(t:integrate(1/(1/300+2*k^2+300*k^4),k,-inf,inf));

and it gives 5*sqrt(3)*pi which i have not checked but assume correct? Anyway obviously the values could have been exactly these for example in the last integral which it gave answer WRONG OF 0.

Discussion

  • Robert Dodier
    Robert Dodier
    2014-07-29

    • Description has changed:

    Diff:

    --- old
    +++ new
    @@ -5,16 +5,23 @@
     Lisp implementation type: GNU Common Lisp (GCL)
     Lisp implementation version: GCL 2.6.8
    
    +~~~~
     (assume(a>1/16,b>4*a,c>4*b),t:integrate(1/(a^2+b^2*k^2+c^2*k^4),k,-inf,inf));
    +~~~~
    
    -Now it is obvious the integral is positive definite and not infinite.
    -it asks is -b^2+2*a+1/8 pos,neg,or 0 and i answer negative and it comes out with WRONG answer of 0.   Next:
    +Now it is obvious the integral is positive definite and not infinite. it asks `is -b^2+2*a+1/8 pos,neg,or 0` and i answer negative and it comes out with WRONG answer of 0.   Next:
    
    +~~~~
     (assume(a>0,a<1/16,b>1,c>4*b),t:integrate(1/(a^2+b^2*k^2+c^2*k^4),k,-inf,inf));
    -Now it asks the same ridiculous question again which has to be negative which is obvious
    -negative from the given assumes  Anyway i answer  negative and again gives WRONG answer 0.
    +~~~~
    +
    +Now it asks the same ridiculous question again which has to be negative which is obvious negative from the given assumes  Anyway i answer  negative and again gives WRONG answer 0.
    
     Next do:
    -(t:integrate(1/(1/300+2*k^2+300*k^4),k,-inf,inf)); and it gives 5*sqrt(3)*pi which  i have not checked but assume correct? Anyway obviously the values  could have been exactly these for 
    -example in the last integral which it gave answer WRONG OF 0.
    
    +~~~~
    +(t:integrate(1/(1/300+2*k^2+300*k^4),k,-inf,inf));
    +~~~~
    +
    +and it gives `5*sqrt(3)*pi` which  i have not checked but assume correct? Anyway obviously the values  could have been exactly these for example in the last integral which it gave answer WRONG OF 0.
    +