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Scaling a bpf-lib

OpenMusic
#1

Hi,
this is a very old problem that, as far as I know, has never been solved. The bpf-scale function seems to work correctly for a single bpf, but when used in a loop for a bpf-lib, it always gives wrong results. I am attaching here a mwe that encapsulates the issue. Is there any chance to fix it? Thanks in advance for all.
Best,
Francesco
bpf-scale mwe.omp (10.9 KB)

#2

Dear Francesco,

This is logical. Since you are scaling THREE different bpfs with the same values.
if you need to have a “correct” sequential bpfs, you should merge the bpfs into one bpf OR consider changing the x0x1y0y1 values at each bpf.

Best
K

#3

Dear Karim,
it’s my bad, the example I chose was not the right one. I’m trying to write a function that scales the bpf-lib as an object (changing the x-min/max and the ymin/max relatively for each bpf), but I get a “bad binding error”. Maybe it’s some silly mistake. Surely you’ll spot right away what does not work here.
Here’s the code:

(in-package :om)

; new method for scaling the entire BPF-lib as an object 

(defmethod! bpf-lib-scale ((self bpf-lib) &key ymin ymax xmin xmax) 
            (let* ((bpflist (bpf-list self))
                   (theymin (list-min (loop for bpf in bpflist collect
                                            (list-min (y-points bpf)))))
                   (theymax (list-max (loop for bpf in bpflist collect
                                            (list-max (y-points bpf)))))
                   (thexmin (list-min (loop for bpf in bpflist collect
                                            (list-min (x-points bpf)))))
                   (thexmax (list-max (loop for bpf in bpflist collect
                                            (list-max (x-points bpf)))))
             

              (print (format nil "ymin=~d ymax=~d xmin=~d xmax=~d" theymin theymax thexmin thexmax))

 (make-instance 'bpf-lib
                             :bpf-list (loop for bpf in bpflist collect
                                             (bpf-from-list (om-scale (x-points bpf) (or xmin thexmin) (or xmax thexmax) thexmin thexmax) 
                                                            (om-scale (y-points bpf) (or ymin theymin) (or ymax theymax) theymin theymax)
                                                            'bpf (decimals bpf)))
              ))))

And here’s the error:
Error while evaluating the box BPF-LIB-SCALE : Bad binding form: (make-instance (quote bpf-lib) :bpf-list (loop for bpf in bpflist collect (bpf-from-list (om-scale (x-points bpf) (or xmin thexmin) (or xmax thexmax) thexmin thexmax) (om-scale (y-points bpf) (or ymin theymin) (or ymax theymax) theymin theymax) (quote bpf) (decimals bpf)))).

Best,
Francesco

#4

Dear Francesco,

Good, but you have some errors in your code. Here it is corrected:
Unnamed.lisp (1.2 KB)

And it works!

Best
K