## 296 Reputation

18 years, 313 days

## solve is misbehaving...

Here is a simple sequcnce of commands that execute without a problem:
restart;
eq1 := 5+3*x=0:
eq2 := 2+7*x-3*y-5*x*y=0:
x:=solve(eq1,x):
y:=solve(eq2,y):
lprint('x'=x,'y'=y);

x = -5/3, y = 29/16

If I put the commands into a procedure there are problems:

## the mysterious "events" command...

Maple

I am using Maple 12.01 and I am using dsolve to solve a second order ODE;  example :

eq:=diff(y(t),t,t)+sin(t)*diff(y(t),t)+y(t)^2-5*y(t)=0;

ic:=a->[D(y)(0)=0,y(0)=a]; # initial conditions.

I want to investigate the  values of z(t, y, y') when g(t, y,y') = 0. Here z might be y''' or cos(t y') and g  might be y(t)-4.

What I would like to do is create an Array whose nth entry is of the form [ tn, z(tn,y(tn), y'(tn)]  where tn is the nth value of t at which the condition g(t, y,y') = 0 is satisfied.

## what is maple doing?...

Maple
Here is a recent session on Maple 12.1. The exact thing happens on Maple 11.5. I define a vector x , Maple acknowledges the fact but then if I ask if x is, in fact, that vector it says no. Any idea of what is going on? with(LinearAlgebra): > x := Vector(2, [1, 0]); Note Maple correctly prints transpose [1 0] on screen. [1] x := [ ] [0] if x=Vector(2, [1, 0]) then 7 else 3 end if; 3 is(x=Vector(2, [1, 0]));

## stop!!!...

Maple
In previous versions of Maple there was an abort/interrupt capability-one could hold down the command key and a period at the same time and eventually Maple would stop the calculation. (Mac worksheet interface). Now there is an interrupt icon which is frequently ignored by Maple. I am currently in an ∞ loop and cannot get out! Help!