1function pointAdd(x1,y1,x2,y2) {
 2    var a = 168700;
 3    var d = 168696;
 4
 5    var res[2];
 6    res[0] = (x1*y2 + y1*x2) / (1 + d*x1*x2*y1*y2);
 7    res[1] = (y1*y2 - a*x1*x2) / (1 - d*x1*x2*y1*y2);
 8    return res;
 9}
10
11template ExpW4Table(k) {
12    signal output out[16][2];
13
14    var i;
15    var p[2];
16
17    var g = [17777552123799933955779906779655732241715742912184938656739573121738514868268,
18             2626589144620713026669568689430873010625803728049924121243784502389097019475];
19
20    var dbl = g;
21
22    for (i=0; i<k*4; i++) {
23        dbl = pointAdd(dbl[0], dbl[1], dbl[0], dbl[1]);
24    }
25
26    out[0][0] <== 0;
27    out[0][1] <== 1;
28    for (i=1; i<16; i++) {
29        p = pointAdd(out[i-1][0], out[i-1][1], dbl[0], dbl[1]);
30        out[i][0] <== p[0];
31        out[i][1] <== p[1];
32    }
33}