newa = tadd(  tsub( tpow(a,8) ,  tmul(tpow(a,10),0.5) )  , point );


q --> q^8 - q^10/2 + c



...Or more explicitly:

q --> tadd(  tsub( tpow(a,8) ,  tmul(tpow(a,10),0.5) )  , c );



... where the above functions are defined as follows:

triplex tadd(triplex a, triplex b) {
	triplex n;
	n.x = a.x + b.x;
	n.y = a.y + b.y;
	n.z = a.z + b.z;
	return n;
}
triplex tsub(triplex a, triplex b) {
	triplex n;
	n.x = a.x - b.x;
	n.y = a.y - b.y;
	n.z = a.z - b.z;
	return n;
}
triplex tdiv(triplex a, double b) {
	triplex n;
	n.x = a.x / b;
	n.y = a.y / b;
	n.z = a.z / b;
	return n;
}
triplex tmul(triplex a, double b) {
	triplex n;
	n.x = a.x * b;
	n.y = a.y * b;
	n.z = a.z * b;
	return n;
}


triplex tpow(triplex a, double p) {
	triplex n;

	double r     = sqrt(a.x*a.x + a.y*a.y + a.z*a.z) ;
	double phi   = atan2( pow(a.x*a.x + a.y*a.y, 0.5) , a.z) ;
	double theta = atan2(a.y , a.x) ;

	r=pow(r,p);	
	yang*=p;	zang*=p;

	n.x = r * sin(phi) * cos(theta);
	n.y = r * sin(phi) * sin(theta);
	n.z = r * cos(phi);
	return n;
}