## matrix equation ... ## how to show the subject's path?...

Hello,

I want to animate a ball rolling on the surface cos(abs(x)+abs(y)).  The ball mass m is 1kg, radius r is 0.1meters starts at (0.5,0.5,cos(abs(5)+abs(5))) meters using g=9.8.

If we say the initial velocity of the ball is pushed in some random direction.

How do I show the path of the ball and animate?

Thanks,

Arthur

## how to do loop with 2 formula...

there’s few redundant values. I just want the positive values. How it can be done?

 > > >  (1)
 > >  (2)
 >                                              (3)
 > > ## How to create Random question with Grading Package...

Hi,

I am exploring the Grading package in Maple, and I want to create a random question about limits. (Question 9). Any ideas for the correct code? Thank you

QUIZZTestMaple.mw

## seq slower than proc ...

I learned about Dodgson calculation of the determinant only recently (https://en.m.wikipedia.org/wiki/Dodgson_condensation).
I am only interested in symbolic expressions of the determinant.
Furthermore, I compared several methods. Not surprisingly, the build in method is the fastest. But why is the seq method slower than the proc method for the Dodgson method? Is there anything I could do to program it more efficiently?

 > > > > > > Dodgson := proc(M::Matrix)  MatrixDet(M); InnerMatrix(M) ^~ (-1) *~ MatrixDet(MatrixDet(M)); do if 1 < RowDimension(%) then InnerMatrix(`%%`) ^~ (-1) *~ MatrixDet(%); end if; until RowDimension(%) = 1; Trace(%): end proc:
 > > >  (1)
 >      