void
wheelArrow(wheelPS *wps, double x0, double y0, double x1, double y1,
double alen, double awidth) {
double len, dir[2], perp[2];
dir[0] = x0 - x1;
dir[1] = y0 - y1;
ELL_2V_NORM(dir, dir, len);
ELL_2V_SET(perp, -dir[1], dir[0]);
fprintf(wps->file, "%g %g M\n", WPS_X(x0), WPS_Y(y0));
fprintf(wps->file, "%g %g L S\n",
WPS_X(x1 + alen*dir[0]/2),
WPS_Y(y1 + alen*dir[1]/2));
if (alen && awidth) {
if (len < alen) {
awidth *= len/alen;
alen = len;
}
fprintf(wps->file, "%g %g M\n",
WPS_X(x1 + alen*dir[0] + awidth*perp[0]),
WPS_Y(y1 + alen*dir[1] + awidth*perp[1]));
fprintf(wps->file, "%g %g L\n", WPS_X(x1), WPS_Y(y1));
fprintf(wps->file, "%g %g L CP F\n",
WPS_X(x1 + alen*dir[0] - awidth*perp[0]),
WPS_Y(y1 + alen*dir[1] - awidth*perp[1]));
}
return;
}
void
ell_2m_1d_nullspace_d(double ans[2], const double _n[4]) {
double n[4], dot, len, span[2];
/* static const char me[]="ell_2m_1d_nullspace_d"; */
ELL_2M_TRANSPOSE(n, _n);
dot = ELL_2V_DOT(n + 2*0, n + 2*1);
/*
fprintf(stderr, "!%s: n = {{%g,%g},{%g,%g}}\n", me,
n[0], n[1], n[2], n[3]);
fprintf(stderr, "!%s: dot = %g\n", me, dot);
*/
if (dot > 0) {
ELL_2V_ADD2(span, n + 2*0, n + 2*1);
} else {
ELL_2V_SUB(span, n + 2*0, n + 2*1);
}
/* have found good description of column span;
now need the (perpendicular) nullspace */
ans[0] = span[1];
ans[1] = -span[0];
ELL_2V_NORM(ans, ans, len);
/*
if (!(AIR_EXISTS(ans[0]) && AIR_EXISTS(ans[1]))) {
fprintf(stderr, "!%s: bad! %g %g\n", me, ans[0], ans[1]);
}
*/
return;
}
void
_ell_22v_enforce_orthogonality(double uu[2], double _vv[2]) {
double dot, vv[2], len;
dot = ELL_2V_DOT(uu, _vv);
ELL_2V_SCALE_ADD2(vv, 1, _vv, -dot, uu);
ELL_2V_NORM(_vv, vv, len);
return;
}