[PD] help cloning max's scale

[Alexandre Torres Porres]

Well, I'm trying to point out that it ain't "broken", the object works...
whatever its code is. I'm just trying to figure out the code to clone it.

2015-06-19 22:55 GMT-03:00 Joel Matthys <jwmatthys at gmail.com>:

>  I just don't see the value of trying to make it compatible with broken
> code in Max.
>
> Joel
>
>
> On 06/19/2015 08:47 PM, Alexandre Torres Porres wrote:
>
> yeah, I see all that, but the problem is trying to clone it as it is in
> Max for the sake of compatibility.
>
>  I wouldn't say that the classic mode is "wrong", it may be not good for
> the purpose, but it's an arbitrary mathematical formula, so it is what it
> is.
>
>  The problem is that I'm not being able to get the result the object
> spits out with the formula given in the reference.
>
>  So my question is just making it sure that the given formula is wrong,
> and that it doesn't give what the object actually does.
>
>  moreover, the idea is to keep compatibility, at first, with Max5. In
> Max7 the scale object will still give the same results (as default, by the
> way), so even if it was for the sake of making it compatible with Max7,
> we'd still need to make it work. But the thing is that the new "not
> classic" mode was introduced only in Max6. So, for the actual purpose,
> we're only caring about the classic mode compatibility.
>
>  did you check if the formula in the reference is actually wrong, in the
> sense it won't give the results given by the object? Were you able to spot
> a parenthesis out of place or something that, if changed, would give the
> expected result?
>
>  thanks
>
>  cheers
>
> 2015-06-19 22:25 GMT-03:00 Joel Matthys <jwmatthys at gmail.com>:
>
>>  You're using the [scale] formula from @classic_mode in Max7, which
>> exists for compatibility with IRCAM, but it's clearly wrong. (There's no
>> way mapping 13.3 from 0-127 to -1 to 1 should result in something so close
>> to -1. Just try a few different exponents and you'll see that there's a bug
>> in the Max code. And there are lots of bug reports out there about it.)
>>
>> That's why they introduced an alternate mode for [scale] in Max, which
>> can be switch in the Inspector.
>>
>> For non-classic (modern) mode, the documentation gives you this equation:
>>
>> ((x-in_low)/(in_high-in_low) == 0) ? out_low :
>> (((x-in_low)/(in_high-in_low)) > 0) ? (out_low + (out_high-out_low) *
>> ((x-in_low)/(in_high-in_low))^exp) : ( out_low + (out_high-out_low) *
>> -((((-x+in_low)/(in_high-in_low)))^(exp)))
>>
>> Translated to expr as:
>>
>> [expr if ((($f1-in_low)/(in_high-in_low)==0), out_low, if
>> ((($f1-in_low)/(in_high-in_low)>0),
>> out_low+(out_high-out_low)*pow(($f1-in_low)/(in_high-in_low), power),
>> out_low+(out_high-out_low)*-1*pow((-1*$f1+in_low)/(in_high-in_low),
>> power)))]
>>
>> Switch off classic mode in the inspector in Max7, and you get the same
>> result as expr above, the very sensible -0.817072.
>>
>> Joel
>>
>>
>> On 06/19/2015 05:39 PM, Alexandre Torres Porres wrote:
>>
>>   Howdy, so I'm cloning the scale object from Max, to make an object and
>> include in the cyclone library. It converts range input (low_in / high_in)
>> to a range output (low_out / high_out). It has a logarithmic curve for
>> rescaling according to a fifth argument/inlet. I did copy into expr the
>> formula described in the reference of Max6/7 (max's 5 was just wrong,
>> copied from [linedrive]) - well, it didn't work! Would anyone know if I'm
>> doing something wrong or if the reference is not telling the truth?
>>
>> The formula, as described in the reference is: (out_low + (out_high-out_low)
>> * ( (out_high - out_low) * exp(-1 * (in_high-in_low) * log(power)) * exp(x
>> * log(power)) ))
>>
>>
>>  Here's my patch with that formula into expr. The output with the
>> parameters I have should be -0.997347 - as that's the output I get in Max.
>> But instead, it's giving -0.994694...
>>
>>
>>  thanks
>>
>>
>>
>>
>>  =================
>>
>>
>>  #N canvas 24 23 488 340 10;
>>
>> #X obj 215 154 v out_low;
>>
>> #X obj 233 132 v out_high;
>>
>> #X obj 288 110 v power;
>>
>> #X obj 152 130 v in_high;
>>
>> #X obj 115 153 v in_low;
>>
>> #X floatatom 58 248 0 0 0 0 - - -;
>>
>> #X obj 58 197 expr (out_low + (out_high-out_low) * ( (out_high - out_low)
>>
>> * exp(-1*(in_high-in_low)*log(power)) * exp($f1*log(power)) ));
>>
>> #X msg 115 102 0;
>>
>> #X msg 152 102 127;
>>
>> #X msg 215 99 -1;
>>
>> #X msg 249 97 1;
>>
>> #X msg 288 86 1.06;
>>
>> #X obj 90 31 loadbang;
>>
>> #X obj 90 60 t b b;
>>
>> #X msg 58 107 13.3;
>>
>> #X connect 6 0 5 0;
>>
>> #X connect 7 0 4 0;
>>
>> #X connect 8 0 3 0;
>>
>> #X connect 9 0 0 0;
>>
>> #X connect 10 0 1 0;
>>
>> #X connect 11 0 2 0;
>>
>> #X connect 12 0 13 0;
>>
>> #X connect 13 0 14 0;
>>
>> #X connect 13 1 11 0;
>>
>> #X connect 13 1 10 0;
>>
>> #X connect 13 1 9 0;
>>
>> #X connect 13 1 8 0;
>>
>> #X connect 13 1 7 0;
>>
>> #X connect 14 0 6 0;
>>
>>
>>
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>>
>
>
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