I got a filter that looks like this:

--------R1----|------R2----|-------
U_in...........L1.............L2........U_out
---------------|-------------|-------
The dots should not be in the illustration but using "space" didn't work...

R1=R2=13 Ohm
L1=L2=25 mH
U_in(t)=1.0*sin(314*t)

I wanted to calculate the angel of U_out in proportion to U_in in radians.
U_L1 = U_in * (ZL1//(R2+ZL2)) / (R1+ZL1//(R2+ZL2)) = 0.234 + j0.283
U_L2 = U_L1 * (ZL2 / (R2+ZL2) = -0.063 + j0.179
The angle for U_L2 = Atan(0.179/(-0.063) = 1.13 rad. This awnser is wrong.
If I go to setup and Complex Mode and set it to r∠θ and enter (-0.063)+0.179i I gives me the right angle of 1.9 rad.

I am guessing that it's me that is stupid but I don't have another calculator to confirm it, so can anyone help me with what I am doing wrong?

Thanks!

Just realized that I could use Wolfram Alpha... it is me that sucks...
Anyone that can explain what I did wrong?

In the future, please use edit instead of double posting also, you can use [code] tags to get good mono space formatting.

I can probably help you out, but I don't quite understand what the // notation is supposed to be, or where you substituted in the complex value that made everything work out.

"//" means parallel so ZL1//(R2+ZL2)=((j*314*25E-3)*(13+j*314*25E-3)) / ((j*314*25E-3)+(13+j*314*25E-3))
L1 and L2 are two coils.
The impedance for a coil is Z=jωL where ω=314.

I will use edit next time

Which is it? This makes no sense.

Sorry, mixed it up a little..
R1=R2=13 Ohm
L1=L2=25 mH

Oh, so looking closer, none of that is actually relevant. Here's the problem. Polar coordinates for a complex number are
Code:
So all we need to do given rectangular coordinates,
Code:
is plugin to
Code:

Trying this, we see

Code:
and sure enough, 1.9 is what you wanted. And....the radius makes sense too:
Code:



If you wanted to get this with arctan, you would have needed the atan2 function, which is aware of which quadrant you're in, and I have no idea if the Prizm implements that. But...atan2(0.179,-0.063) also = 1.9.

No, the first stuff didn't matter but I thinks it's good to show the whole problem instead of just a part of it if it might be a problem in there too...

Thanks for the help!

This is a handy website to keep in mind

http://asciiflow.com/

it lets you draw block diagrams and circuits using ASCII characters, then you can copy and paste them in to comments using a monospace font.