Differences between the different solve/zeros commands?
10-23-2014, 11:36 PM
Post: #1
 pr0 Junior Member Posts: 5 Joined: Sep 2014
Differences between the different solve/zeros commands?
What are the differences between the different solve/zeros commands and which commands are recommended when?

Trying to solve this for x but cant find a working command:

ARG((-e^(-0.3*i*x))/(x^2-i*x))=-165

Any help would be really appreciated!
10-24-2014, 01:05 AM
Post: #2
 Don Shepherd Senior Member Posts: 749 Joined: Dec 2013
RE: Differences between the different solve/zeros commands?
(10-23-2014 11:36 PM)pr0 Wrote:  What are the differences between the different solve/zeros commands and which commands are recommended when?

Trying to solve this for x but cant find a working command:

ARG((-e^(-0.3*i*x))/(x^2-i*x))=-165

Any help would be really appreciated!

What calculator?
10-24-2014, 06:18 AM
Post: #3
 rkf Member Posts: 78 Joined: Apr 2014
RE: Differences between the different solve/zeros commands?
(10-24-2014 01:05 AM)Don Shepherd Wrote:  ...
What calculator?

Since this forum is named "HP Prime", the HP Prime?
10-24-2014, 08:04 AM
Post: #4
 parisse Senior Member Posts: 1,327 Joined: Dec 2013
RE: Differences between the different solve/zeros commands?
This equation has no solution. If you take exp(0.3*i*x), x must be in radians, therefore argument should be rescaled in -pi..pi.
fsolve(arg((-e^(-0.3*i*x))/(x^2-i*x))=-165*pi/180,x=-10..10)
returns 2 solutions.
10-25-2014, 10:01 PM
Post: #5
 pr0 Junior Member Posts: 5 Joined: Sep 2014
RE: Differences between the different solve/zeros commands?
(10-24-2014 08:04 AM)parisse Wrote:  This equation has no solution. If you take exp(0.3*i*x), x must be in radians, therefore argument should be rescaled in -pi..pi.
fsolve(arg((-e^(-0.3*i*x))/(x^2-i*x))=-165*pi/180,x=-10..10)
returns 2 solutions.

Thanks! When is fsolve recommended and when is other commands recommended for solving? Any other cases radians must be selected?
10-26-2014, 07:34 AM
Post: #6
 parisse Senior Member Posts: 1,327 Joined: Dec 2013
RE: Differences between the different solve/zeros commands?
fsolve is recommended if you want a numeric answer, solve if you want a symbolic answer (but solve can only find roots for polynomial-like equations).
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