## 1080 Reputation

16 years, 152 days

## sqrt(x^2)...

Maple
If you ask most people "what is the square root of 64?" they will answer "8". Of course we know that the technically correct answer is {8,-8}. So I'm a bit confused that when I ask MAPLE to simplify sqrt(x^2) it spits the expression right back to me, but when I tell MAPLE to give me sqrt(x^2) assuming x>0 it gives me x. It seems to me that there are going to be two answers whether or not x>0. That is, the answer to sqrt(x^2) is {x,-x} whether or not x>0. That is, sqrt((-8)^2) = sqrt(8^2) = {8,-8}. So when I am using symbols rather than numbers why does MAPLE give me the answer x for sqrt(x^2) assuming x>0, but give me the answer sqrt(x^2) when I don't include the assumption?

## reevaluating en expression...

Maple
Suppose I have the following in my worksheet > a:=17 > expr1 := a^2 +4: > expr1 293 > a:= 0: > expr1 293 Its clear what's happening - expr1 was defined when a was 17 and it doesn't change just because later I change the value of a. I understand that after I set a equal to 0, if I had moved the cursor up to the line where expr1 was defined and pressed the ! button the value of expr1 would change to reflect the new value of a. My question is, is there any function in MAPLE such as redefine(expr1) which will in effect move the cursor to the line on which expr1 was defined, press !, and then move the cursor back to wherever it was?

## Formating live math output in a document...

Maple
In my worksheet I have a variable Q which has a value of 0.000002859716408. I am in a document block and type The value of Q and then I press ctrl= and the line reads The value of Q = 0.000002859716408 But what if I had wanted the value to be outputted in scientific format, e. g. The value of Q = 2.85972e-06 Is there any way I could have gotten this output ? Thanks

## Unassign from within a procedure...

Maple
Hello. I was wondering if it is possible to unassign a variable from within a procedure. The accompanying file illustrates what I am trying to do. As always, my anticipated thanks to anyone kind enough to take the time to help me. I would be totally lost in MAPLE without this forum. a href='http://maplenet.maplesoft.com/maplenet/worksheet/mapleprimes/2292_Unassign within a procedure.mw'>View 2292_Unassign within a procedure.mw on MapleNet or Download 2292_Unassign within a procedure.mw

## Using Matirx equations...

Maple
I wonder if someone could help explain to me how to use Matrix equations. Suppose A is a 3x3 matrix of constants, b a 3 vector of variables (x,y,z) and c a 3 vector of constants. The equation A.b = c is really 3 equations in x y z. Is it possible to extract those equations from the matrix equation A.b = c? I explain my question more clearly in the uploaded worksheet. Thanks The link can be found in the File Manager Vie
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