## 33 Reputation

16 years, 158 days

## about "remove" and " select"...

Maple

On the help page, the description says the remove function does the opposite of select.
when I run:

remove(has, D[1](xx[0]), {xx[0]})

it gives: D[1]()

while: select(has, D[1](xx[0]), {xx[0]})

produces: D[1](xx[0])

I find this during programming.

Is there a way to remove the whole expression "D[1](xx[0])"

Many thanks!

## about "abs" command...

Maple

abs(-((-(1/20)*sqrt(5)-1/20)*cos((1/5)*Pi)-(1/20)*sqrt(2)*sqrt(5-sqrt(5))*sin((1/5)*Pi))*24^(1/5)*5^(3/5)-I*((1/20)*sqrt(2)*sqrt(5-sqrt(5))*cos((1/5)*Pi)+(-(1/20)*sqrt(5)-1/20)*sin((1/5)*Pi))*24^(1/5)*5^(3/5))

I am trying to compute the modulus the above complex number. However, the "abs" command does not affect the complex expression. Any reason for this?

Many thanks!

## solutions of sin (x)...

Maple

Is there any way to solve sin(x)=0 with solutions x=k*pi in Maple?

Many thanks!

## How to animate the complex plot?...

Maple

I tried to find the root distritubion of a polynomial?

When p=1, q=3, the following command works.

with(plots):

eq:=u^(2*q)+1-2*K*u^(q-p);

p:=1;   q:=3;

unitcircle:=implicitplot(x^2+y^2 = 1, x = -1 .. 1, y = -1 .. 1, scaling = constrained);

animate(complexplot,[[solve(eq, u)],style = point,symbolsize=10,color="red"],frames=50,K=-1..1,background=unitcircle, scaling=constrained, trace=20 );

However, when I tried p=2, q=3, only one root was shown on the animation.

But   "complexplot([solve(eq,u)],style=point)"      showed  6 roots anyway.

I have no idea what was wrong.

## about 'factor' during simplifying...

Maple

Dear all,

The results I get from calcultion are usually not in compact forms, so I want to do some simplifying work. And I come up with some questions.

If I write the following expression, the factor command works:
> beta[c]^3/exp(I*omega[c]*tau)-beta[c]^2/(exp(I*omega[c]*tau))^2-2*beta[c]^2+2*beta[c]/exp(I*omega[c]*tau)+beta[c]*exp(I*omega[c]*tau)-1;
> factor(%);

However,when I write the above expressoin as following,  factor doesn't work

 1 2 Page 1 of 2
﻿