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### gain~&linedrive~ equation

Sep 30 2007 | 4:28 pm

Hi all,

does anybody know what exactly is the equation used in the linedrive~ and gain~ objects? (See the reference manual) I think it is not clearly stated.

Is it y = b*e – a*log(c)*e*x*log(c)

or y = b*exp{-a*log(c)}*e{x*log(c)}

or what?

I want to know what exactly is the output of my gain~ object is, so I need to know this detail.

Thank you,

FunnyZen

Oct 01 2007 | 8:02 am

On 30 Sep 2007, at 18:28, FunnyZen wrote:

>
> Hi all,
>
> does anybody know what exactly is the equation used in the
> linedrive~ and gain~ objects? I think it is not clearly stated.
>
> Is it y = b*e – a*log(c)*e*x*log(c)
>
> or y = b*exp{-a*log(c)}*e{x*log(c)}
>
> or what?

i would say the latter is the right direction. i believe it’s quite
clearly stated in the reference manual.
vb

#P window setfont "Sans Serif" 9.;
#P flonum 196 206 65 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
#P flonum 70 206 65 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
#P window linecount 1;
#P newex 196 179 260 196617 expr 1. * exp(-127.*log(1.06)) * exp
(\$f1*log(1.06));
#P number 70 133 35 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
#P user hslider 70 108 18 128 128 1 0 0;
#P newex 70 181 120 196617 linedrive 127 1. 1.06 30;
#B color 5;
#P connect 1 0 2 0;
#P connect 2 0 0 0;
#P connect 0 0 4 0;
#P connect 2 0 3 0;
#P connect 3 0 5 0;
#P window clipboard copycount 6;

Oct 05 2007 | 5:38 pm

I think you’re right. But where did you get this line

#P newex 196 179 260 196617 expr 1. * exp(-127.*log(1.06)) * exp
(\$f1*log(1.06));

Here yes, it is clearly stated. But in the msp reference manual the given equation is

y = b e-a log c ex log c

which is certainly a wrong way to give an equation and certainly not clear, it could match to many different equations. Perfectly clear is something like this

y = b * exp{-a*log(c)} * exp{x*log(c)}

Dimitris

Oct 05 2007 | 8:00 pm

On 05 Oct 2007, at 19:38, FunnyZen wrote:

>
> I think you’re right. But where did you get this line
>
> #P newex 196 179 260 196617 expr 1. * exp(-127.*log(1.06)) * exp
> (\$f1*log(1.06));
>
> Here yes, it is clearly stated. But in the msp reference manual the
> given equation is
>
> y = b e-a log c ex log c

you are right. in the msp reference of [gain~] the math font got lost
somehow.
it’s correct in the Max reference of [linedrive], and that’s where i
got it from.
vb

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