static GEN
bound_for_coeff(long m, GEN rr, GEN *maxroot)
{
long i,r1, lrr=lg(rr);
GEN p1,b1,b2,B,M, C = matpascal(m-1);
for (r1=1; r1 < lrr; r1++)
if (typ(rr[r1]) != t_REAL) break;
r1--;
rr = gabs(rr,0); *maxroot = vecmax(rr);
for (i=1; i<lrr; i++)
if (gcmp(gel(rr,i), gen_1) < 0) gel(rr,i) = gen_1;
for (b1=gen_1,i=1; i<=r1; i++) b1 = gmul(b1, gel(rr,i));
for (b2=gen_1 ; i<lrr; i++) b2 = gmul(b2, gel(rr,i));
B = gmul(b1, gsqr(b2)); /* Mahler measure */
M = cgetg(m+2, t_VEC); gel(M,1) = gel(M,2) = gen_0; /* unused */
for (i=1; i<m; i++)
{
p1 = gadd(gmul(gcoeff(C, m, i+1), B),/* binom(m-1, i) */
gcoeff(C, m, i)); /* binom(m-1, i-1) */
gel(M,i+2) = ceil_safe(p1);
}
return M;
}
void line(CANVAS* canvas, const POINT *a, const POINT *b, unsigned int color)
{
POINT cur;
bool vline;
short x0, x1, y0, y1, dx, dy, err, ystep, x, y;
x0 = a->x;
y0 = a->y;
x1 = b->x;
y1 = b->y;
vline = gabs(y1 - y0) > gabs(x1 - x0);
if (vline)
{
gswap(&x0, &y0);
gswap(&x1, &y1);
}
if (x0 > x1)
{
gswap(&x0, &x1);
gswap(&y0, &y1);
}
dx = x1 - x0;
dy = gabs(y1 - y0);
err = dx >> 1;
ystep = (y0 < y1) ? 1 : -1;
for (x = x0, y = y0; x <= x1; ++x)
{
if (vline)
{
cur.x = y;
cur.y = x;
}
else
{
cur.x = x;
cur.y = y;
}
put_pixel(canvas, &cur, color);
err -= dy;
if (err < 0)
{
y += ystep;
err += dx;
}
}
}
