it works here, double check your order of operations:

#N canvas 131 195 450 300 12;
#X msg 119 70 1 0 1.5708;
#X floatatom 119 140 15 0 0 0 - - - 0;
#X floatatom 361 137 5 0 0 0 - - - 0;
#X obj 119 95 expr ($f1*cos($f3))-($f2*sin($f3)) \; ($f1*sin($f3))+($f2*cos($f3));
#X connect 0 0 3 0;
#X connect 3 0 1 0;
#X connect 3 1 2 0;

Antoine


Le dim. 14 déc. 2025 à 11:56, Hrvoje Radnic via Pd-list <pd-list@lists.iem.at> a écrit :
Thank you Miller for your suggestion. I don't think that's the case, I checked the order of operations with [print] and everything looks like it should. I even made the signal version of the whole [expr] computation in order to bypass the possibility of wrong order and the result is repeated there as well. So, it must be math inside [expr], but I really struggle to find any clue. 



On Saturday, November 29, 2025 at 04:40:48 PM GMT+1, Miller Puckette via Pd-list <pd-list@lists.iem.at> wrote:


Are you by any chance updating x before running the y calculation? If
you do that, y will be
calculated using the updated x and not the correct (original) one.

cheers
Miller

On 11/29/25 6:49 AM, Hrvoje Radnic via Pd-list wrote:
> Dear group,
>
> I cannot figure out why the calculations inside
>  [expr (x*cos(theta))-(y*sin(theta));
> (x*sin(theta))+(y*cos(theta))] gives me wrong results.
>
> The above mentioned formula for rotation is correct. I initialize the
> values through [value] object before preforming computation. The
> initial values are: x=1, y=0, theta=1/2pi. I expect  the new x and new
> y to be (0,1) respectively after the rotation. But, for some reason, I
> get (-1,1). I checked the help files for [value] and [expr] and it
> looks like I am doing everything right.
> Anyone have an idea where's the mistake?
> Thank you!
> Hrvoje Radnic
>
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