mirror of
https://github.com/NGSolve/netgen.git
synced 2024-11-16 02:48:33 +05:00
380 lines
8.4 KiB
C++
380 lines
8.4 KiB
C++
#include <mystdlib.h>
|
|
|
|
#include <myadt.hpp>
|
|
#include <meshing.hpp>
|
|
#include <csg.hpp>
|
|
#include <stlgeom.hpp>
|
|
|
|
#include "fieldlines.hpp"
|
|
|
|
namespace netgen
|
|
{
|
|
RKStepper :: ~RKStepper()
|
|
{
|
|
delete a;
|
|
}
|
|
|
|
RKStepper :: RKStepper(int type) : a(NULL), tolerance(1e100)
|
|
{
|
|
notrestarted = 0;
|
|
|
|
if (type == 0) // explicit Euler
|
|
{
|
|
c.SetSize(1); c[0] = 0;
|
|
b.SetSize(1); b[0] = 1;
|
|
steps = order = 1;
|
|
}
|
|
else if (type == 1) // Euler-Cauchy
|
|
{
|
|
c.SetSize(2); c[0] = 0; c[1] = 0.5;
|
|
b.SetSize(2); b[0] = 0; b[1] = 1;
|
|
NgArray<int> size(2);
|
|
size[0] = 0; size[1] = 1;
|
|
a = new TABLE<double>(size);
|
|
a->Set(2,1,0.5); // Set, Get: 1-based!
|
|
steps = order = 2;
|
|
}
|
|
else if (type == 2) // Simpson
|
|
{
|
|
c.SetSize(3); c[0] = 0; c[1] = 1; c[2] = 0.5;
|
|
b.SetSize(3); b[0] = b[1] = 1./6.; b[2] = 2./3.;
|
|
NgArray<int> size(3);
|
|
size[0] = 0; size[1] = 1; size[2] = 2;
|
|
a = new TABLE<double>(size);
|
|
a->Set(2,1,1);
|
|
a->Set(3,1,0.25); a->Set(3,2,0.25);
|
|
steps = order = 3;
|
|
}
|
|
else if (type == 3) // classical Runge-Kutta
|
|
{
|
|
c.SetSize(4); c[0] = 0; c[1] = c[2] = 0.5; c[3] = 1;
|
|
b.SetSize(4); b[0] = b[3] = 1./6.; b[1] = b[2] = 1./3.;
|
|
NgArray<int> size(4);
|
|
size[0] = 0; size[1] = 1; size[2] = 2; size[3] = 3;
|
|
a = new TABLE<double>(size);
|
|
a->Set(2,1,0.5);
|
|
a->Set(3,1,0); a->Set(3,2,0.5);
|
|
a->Set(4,1,0); a->Set(4,2,0); a->Set(4,3,1);
|
|
steps = order = 4;
|
|
}
|
|
|
|
K.SetSize(steps);
|
|
}
|
|
|
|
void RKStepper :: StartNextValCalc(const Point<3> & astartval, const double astartt, const double ah, const bool aadaptive)
|
|
{
|
|
//cout << "Starting RK-Step with h=" << ah << endl;
|
|
|
|
stepcount = 0;
|
|
h = ah;
|
|
startt = astartt;
|
|
startval = astartval;
|
|
adaptive = aadaptive;
|
|
adrun = 0;
|
|
}
|
|
|
|
bool RKStepper :: GetNextData(Point<3> & val, double & t, double & ah)
|
|
{
|
|
bool finished = false;
|
|
|
|
if(stepcount <= steps && stepcount>0)
|
|
{
|
|
t = startt + c[stepcount-1]*h;
|
|
val = startval;
|
|
for(int i=0; i<stepcount-1; i++)
|
|
val += h * a->Get(stepcount,i+1) * K[i];
|
|
}
|
|
|
|
|
|
if(stepcount == steps)
|
|
{
|
|
val = startval;
|
|
for(int i=0; i<steps; i++)
|
|
val += h * b[i] * K[i];
|
|
|
|
if(adaptive)
|
|
{
|
|
if(adrun == 0)
|
|
{
|
|
stepcount = 0;
|
|
h *= 0.5;
|
|
adrun = 1;
|
|
valh = val;
|
|
}
|
|
else if (adrun == 1)
|
|
{
|
|
stepcount = 0;
|
|
startval_bak = startval;
|
|
startval = val;
|
|
startt_bak = startt;
|
|
startt += h;//0.5*h;
|
|
adrun = 2;
|
|
}
|
|
else if (adrun == 2)
|
|
{
|
|
Point<3> valh2 = val;
|
|
val = valh2 + 1./(pow(2.,order)-1.) * (valh2 - valh);
|
|
auto errvec = val - valh;
|
|
|
|
double err = errvec.Length();
|
|
|
|
double fac = 0.7 * pow(tolerance/err,1./(order+1.));
|
|
if(fac > 1.3) fac = 1.3;
|
|
|
|
if(fac < 1 || notrestarted >= 2)
|
|
ah = 2.*h * fac;
|
|
|
|
if(err < tolerance)
|
|
{
|
|
finished = true;
|
|
notrestarted++;
|
|
//(*testout) << "finished RK-Step, new h=" << ah << " tolerance " << tolerance << " err " << err << endl;
|
|
}
|
|
else
|
|
{
|
|
//ah *= 0.9;
|
|
notrestarted = 0;
|
|
//(*testout) << "restarting h " << 2.*h << " ah " << ah << " tolerance " << tolerance << " err " << err << endl;
|
|
StartNextValCalc(startval_bak,startt_bak, ah, adaptive);
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
t = startt + h;
|
|
finished = true;
|
|
}
|
|
|
|
}
|
|
|
|
if(stepcount == 0)
|
|
{
|
|
t = startt + c[stepcount]*h;
|
|
val = startval;
|
|
for(int i=0; i<stepcount; i++)
|
|
val += h * a->Get(stepcount,i) * K[i];
|
|
}
|
|
|
|
return finished;
|
|
}
|
|
|
|
|
|
bool RKStepper :: FeedNextF(const Vec<3> & f)
|
|
{
|
|
K[stepcount] = f;
|
|
stepcount++;
|
|
return true;
|
|
}
|
|
|
|
|
|
|
|
void FieldLineCalc :: GenerateFieldLines(Array<Point<3>> & potential_startpoints, const int numlines)
|
|
{
|
|
|
|
|
|
Array<Point<3>> line_points;
|
|
Array<double> line_values;
|
|
Array<bool> drawelems;
|
|
Array<int> dirstart;
|
|
pstart.SetSize0();
|
|
pend.SetSize0();
|
|
values.SetSize0();
|
|
|
|
double crit = 1.0;
|
|
|
|
if(randomized)
|
|
{
|
|
double sum = 0;
|
|
double lami[3];
|
|
Vec<3> v;
|
|
|
|
for(int i=0; i<potential_startpoints.Size(); i++)
|
|
{
|
|
int elnr = mesh.GetElementOfPoint(potential_startpoints[i],lami,true) - 1;
|
|
if(elnr == -1)
|
|
continue;
|
|
|
|
mesh.SetPointSearchStartElement(elnr);
|
|
|
|
func(elnr, lami, v);
|
|
sum += v.Length();
|
|
}
|
|
|
|
crit = sum/double(numlines);
|
|
}
|
|
|
|
|
|
int calculated = 0;
|
|
|
|
for(int i=0; i<potential_startpoints.Size(); i++)
|
|
{
|
|
if(randomized)
|
|
SetCriticalValue((double(rand())/RAND_MAX)*crit);
|
|
|
|
if(calculated >= numlines) break;
|
|
|
|
Calc(potential_startpoints[i],line_points,line_values,drawelems,dirstart);
|
|
|
|
bool usable = false;
|
|
|
|
for(int j=1; j<dirstart.Size(); j++)
|
|
for(int k=dirstart[j-1]; k<dirstart[j]-1; k++)
|
|
{
|
|
if(!drawelems[k] || !drawelems[k+1]) continue;
|
|
|
|
usable = true;
|
|
pstart.Append(line_points[k]);
|
|
pend.Append(line_points[k+1]);
|
|
values.Append( 0.5*(line_values[k]+line_values[k+1]) );
|
|
}
|
|
|
|
if(usable) calculated++;
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
FieldLineCalc :: FieldLineCalc(const Mesh & amesh, const VectorFunction & afunc,
|
|
const double rel_length, const int amaxpoints,
|
|
const double rel_thickness, const double rel_tolerance, const int rk_type, const int adirection) :
|
|
mesh(amesh), func(afunc), stepper(rk_type)
|
|
{
|
|
mesh.GetBox (pmin, pmax);
|
|
rad = 0.5 * Dist (pmin, pmax);
|
|
|
|
|
|
maxlength = (rel_length > 0) ? rel_length : 0.5;
|
|
maxlength *= 2.*rad;
|
|
|
|
thickness = (rel_thickness > 0) ? rel_thickness : 0.0015;
|
|
thickness *= 2.*rad;
|
|
|
|
double auxtolerance = (rel_tolerance > 0) ? rel_tolerance : 1.5e-3;
|
|
auxtolerance *= 2.*rad;
|
|
|
|
stepper.SetTolerance(auxtolerance);
|
|
|
|
direction = adirection;
|
|
|
|
|
|
maxpoints = amaxpoints;
|
|
|
|
if(direction == 0)
|
|
{
|
|
maxlength *= 0.5;
|
|
maxpoints /= 2;
|
|
}
|
|
|
|
|
|
critical_value = -1;
|
|
|
|
randomized = false;
|
|
|
|
}
|
|
|
|
|
|
FieldLineCalc :: ~FieldLineCalc() {;}
|
|
|
|
|
|
void FieldLineCalc :: Calc(const Point<3> & startpoint, Array<Point<3>> & points, Array<double> & vals, Array<bool> & drawelems, Array<int> & dirstart)
|
|
{
|
|
Vec<3> v = 0.0;
|
|
double startlami[3] = {0.0, 0.0, 0.0};
|
|
|
|
points.SetSize(0);
|
|
vals.SetSize(0);
|
|
drawelems.SetSize(0);
|
|
|
|
dirstart.SetSize(0);
|
|
dirstart.Append(0);
|
|
|
|
|
|
int startelnr = mesh.GetElementOfPoint(startpoint,startlami,true) - 1;
|
|
(*testout) << "p = " << startpoint << "; elnr = " << startelnr << endl;
|
|
if (startelnr == -1)
|
|
return;
|
|
|
|
mesh.SetPointSearchStartElement(startelnr);
|
|
|
|
Vec<3> startv;
|
|
bool startdraw = func(startelnr, startlami, startv);
|
|
|
|
double startval = startv.Length();
|
|
|
|
if(critical_value > 0 && fabs(startval) < critical_value)
|
|
return;
|
|
|
|
//cout << "p = " << startpoint << "; elnr = " << startelnr << endl;
|
|
|
|
|
|
|
|
for(int dir = 1; dir >= -1; dir -= 2)
|
|
{
|
|
if(dir*direction < 0) continue;
|
|
|
|
points.Append(startpoint);
|
|
vals.Append(startval);
|
|
drawelems.Append(startdraw);
|
|
|
|
double h = 0.001*rad/startval; // otherwise no nice lines; should be made accessible from outside
|
|
|
|
v = startv;
|
|
if(dir == -1) v *= -1.;
|
|
|
|
int elnr = startelnr;
|
|
double lami[3] = { startlami[0], startlami[1], startlami[2]};
|
|
|
|
|
|
for(double length = 0; length < maxlength; length += h*vals.Last())
|
|
{
|
|
if(v.Length() < 1e-12*rad)
|
|
{
|
|
(*testout) << "Current fieldlinecalculation came to a stillstand at " << points.Last() << endl;
|
|
break;
|
|
}
|
|
|
|
double dummyt{0};
|
|
stepper.StartNextValCalc(points.Last(),dummyt,h,true);
|
|
stepper.FeedNextF(v);
|
|
bool drawelem = false;
|
|
|
|
Point<3> newp;
|
|
while(!stepper.GetNextData(newp,dummyt,h) && elnr != -1)
|
|
{
|
|
elnr = mesh.GetElementOfPoint(newp,lami,true) - 1;
|
|
if(elnr != -1)
|
|
{
|
|
mesh.SetPointSearchStartElement(elnr);
|
|
drawelem = func(elnr, lami, v);
|
|
if(dir == -1) v *= -1.;
|
|
stepper.FeedNextF(v);
|
|
}
|
|
}
|
|
|
|
if (elnr == -1)
|
|
{
|
|
//cout << "direction " <<dir << " reached the wall." << endl;
|
|
break;
|
|
}
|
|
|
|
points.Append(newp);
|
|
vals.Append(v.Length());
|
|
drawelems.Append(drawelem);
|
|
|
|
if(points.Size() % 40 == 0 && points.Size() > 1)
|
|
(*testout) << "Points in current fieldline: " << points.Size() << ", current position: " << newp << endl;
|
|
|
|
if(maxpoints > 0 && points.Size() >= maxpoints)
|
|
{
|
|
break;
|
|
}
|
|
|
|
//cout << "length " << length << " h " << h << " vals.Last() " << vals.Last() << " maxlength " << maxlength << endl;
|
|
}
|
|
dirstart.Append(points.Size());
|
|
}
|
|
}
|
|
|
|
}
|