Differences between the different solve/zeros commands?

[pr0]

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!

[Don Shepherd]

(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?

[rkf]

(10-24-2014 01:05 AM)Don Shepherd Wrote:  ...
What calculator?

Since this forum is named "HP Prime", the HP Prime?

[parisse]

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.

[pr0]

(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?

[parisse]

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).