- #1

- 93

- 0

## Main Question or Discussion Point

Hello everyone,

I copy-paste here a little bit of code:

The quantities x and y are calculated elsewhere.

The expression 1 for the arctangent is wrong since it gives me -pi/2

In expression 2, I chop the arguments and the result is right.

Expression 3 is used when x or y is complex and gives the right answer as well.

Finally, some tests…

Any thoughts ?

TIA

I copy-paste here a little bit of code:

Code:

```
In[4417]:= x = (1.5` + 0.` I);
y = (0.` + 0.` I);
(* 1 *) ArcTan[x, y]
(* 2 *) ArcTan[x // Chop, y // Chop]
(* 3 *) -I Log[(x + I y)/Sqrt[x^2 + y^2]]
{y == 0, Re[y] == 0, Im[y] == 0, Im[x] == 0}
Out[4419]= -1.5708 + 0. I
Out[4420]= 0
Out[4421]= 0. + 0. I
Out[4422]= {True, True, True, True}
```

The expression 1 for the arctangent is wrong since it gives me -pi/2

In expression 2, I chop the arguments and the result is right.

Expression 3 is used when x or y is complex and gives the right answer as well.

Finally, some tests…

Any thoughts ?

TIA