Codebox is killing me - I don't understand the variable declaration it seems

so the cool code below is the 'port'. it is a basic biquad, with some magic love in the feedback loop.

2 questions:
1) I get an error at the line "b0a0 = b0/a0;" telling me that b0 is not declared. it is in my if else if, in principle. I had to remove a 'case' and put numbers as it seems the if comparison did not want to compare to "bandpass' and such... anyway, I don't get why it does not initialise properly.

2) optimisation wise: I don't want to have the coefficients to be calculated at audio rate. Should I just do an abstraction and do the maths elsewhere?

3) why gen~ you might ask? Simple: I wanted to see if I could port easily some code for even faster prototyping, which is the sales pitch I think. Anyway, I will go to mxj~ soon but I'm open to any suggestion

thanks all

pa

//    Butt~ - a dirty filter based on a basic biquad...
//    by Pierre Alexandre Tremblay
// v.2 - optimised at the University of Huddersfield, thanks to the hints and discussions with Peter Castine, Alex Harker, Kit Clayton and Apple Dev Website
// v.3 in gen~

// the methods

Param freq(666,min=1,max=20000);
Param bw(1,min=0.01,max=100);
Param dirt(0,min=0,max=1);
Param type(3);

// the delays

History b_in1, b_in2, b_ou1, b_ou2;
b_in0 = in1;

// constants

temp_ln=0.34657359027997265471;
b_piDsr=(2. * pi) / samplerate;

// process bandwidth
omega = (b_piDsr) * (freq);
tsin = sin(omega);
tcos = cos(omega);
alpha = tsin * sinh(temp_ln * (bw) * omega / tsin);        // bandwidth

// then process coefficients
if(type == 1) {
    b0=(1.0-tcos)/2.0;
    b1=1.0-tcos;
    b2=(1.0-tcos)/2.0;
    a0=1.0+alpha;
    a1=-2.0*tcos;
    a2=1.0-alpha;
}
else if(type == 2) {
    b0 = (1.0 + tcos) /2.0;
    b1 = -(1.0 + tcos);
    b2 = (1.0 + tcos) /2.0;
    a0 = 1.0 + alpha;
    a1 = -2.0 * tcos;
    a2 = 1.0 - alpha;
}
else if (type == 3) {
    b0=alpha;
    b1=0.0;
    b2=-alpha;
    a0=1.0+alpha;
    a1=-2.0*tcos;
    a2=1.0-alpha;
}
else if (type == 4) {
b0 = 1.0;
    b1 = -2.0 * tcos;
b2 = 1.0;
    a0 = 1.0 + alpha;
    a1 = -2.0 * tcos;
a2 = 1.0 - alpha;
}

b0a0 = b0/a0;
b1a0 = b1/a0;
b2a0 = b2/a0;
a1a0 = a1/a0;
a2a0 = a2/a0;        

out1 = b0a0*b_in0 + b1a0*b_in1 + b2a0*b_in2 - a1a0*b_ou1 - a2a0*b_ou2;

b_in2 = b_in1 * (1. - (dirt * noise())); // adding some dirty to the buffers!
b_in1 = b_in0 * (1. - (dirt * noise()));
b_ou2 = b_ou1 * (1. - (dirt * noise()));
b_ou1 = out1 * (1. - (dirt * noise()));