jsketcher/web/app/math/optim.js
2014-10-20 19:49:09 -07:00

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8.8 KiB
JavaScript

TCAD.optim = {};
// convergence Rough 1e-8
// convergence Fine 1e-10
TCAD.math.solve_BFGS = function(subsys, convergence, smallF) {
var xsize = subsys.params.length;
if (xsize == 0) {
return "Success";
}
var xdir; //Vector
var B = new TCAD.math.Matrix(xsize, xsize);
B.identity();
var x = new TCAD.math.Vector(xsize);
var grad = new TCAD.math.Vector(xsize);
var h = new TCAD.math.Vector(xsize);
var y = new TCAD.math.Vector(xsize);
// Initial unknowns vector and initial gradient vector
TCAD.math.fillParams(subsys, x.data);
subsys.calcGrad(grad.data);
// Initial search direction oposed to gradient (steepest-descent)
xdir = grad.scalarMultiply(-1);
TCAD.math.lineSearch(subsys, xdir);
var err = subsys.errorSquare();
h = x.copy();
TCAD.math.fillParams(subsys, x.data);
h = x.subtract(h); // = x - xold
var maxIterNumber = 100 * xsize;
var divergingLim = 1e6*err + 1e12;
for (var iter=1; iter < maxIterNumber; iter++) {
if (h.norm() <= convergence || err <= smallF)
break;
if (err > divergingLim || err != err) // check for diverging and NaN
break;
y = grad.copy();
subsys.calcGrad(grad.data);
y = grad.subtract(y); // = grad - gradold
//Now calculate the BFGS update on B
// TCAD.math.bfgsUpdate(B, h, y);
TCAD.math.bfgsUpdateInverse(B, y, h);
xdir = B.multiply(grad).scalarMultiply(-1);
// xdir = grad.scalarMultiply(-1);
TCAD.math.lineSearch(subsys, xdir);
err = subsys.errorSquare();
h = x.copy();
TCAD.math.fillParams(subsys, x.data);
h = x.subtract(h); // = x - xold
}
if (err <= smallF)
return "Success";
if (h.norm() <= convergence)
return "Converged";
return "Failed";
};
TCAD.math.fillParams = function(sys, out) {
for (var p = 0; p < sys.params.length; p++) {
out[p][0] = sys.params[p].get();
}
};
TCAD.math.setParams2 = function(sys, point) {
for (var p = 0; p < sys.params.length; p++) {
sys.params[p].set(point[p][0]);
}
};
TCAD.math.bfgsUpdateInverse = function(H, y, s) {
// 18.16
var I = new TCAD.math.Matrix(s.rSize, s.rSize);
I.identity();
var yT = y.transpose();
var sT = s.transpose();
var yT_x_s = y.dot(s);
if (yT_x_s == 0) yT_x_h = .0000000001;
var p = 1 / yT_x_s;
var A = I.subtract( s.multiply(yT).scalarMultiply(p) )
var B = I.subtract( y.multiply(sT).scalarMultiply(p) )
var C = s.multiply(sT).scalarMultiply(p)
return A.multiply(H).multiply(C).add(C);
};
TCAD.math.bfgsUpdate = function(B, y, h) {
var B_x_h = B.multiply(h);
var hT_x_B = h.transpose().multiply(B);
var yT = y.transpose();
var y_x_yT = y.multiply(yT);
var yT_x_h = y.dot(h);
var hT_x_B_x_h = h.dot(B_x_h)
if (yT_x_h == 0) yT_x_h = .0000000001;
if (hT_x_B_x_h == 0) hT_x_B_x_h = .0000000001;
B = B.add( y_x_yT.scalarMultiply( 1 / yT_x_h ) );
B = B.subtract( ( B_x_h.multiply(hT_x_B) ).scalarMultiply( 1./hT_x_B_x_h ) );
};
TCAD.math.solve_SD = function(subsys) {
var i = 0;
var grad = new TCAD.math.Vector(subsys.params.length);
while (subsys.errorSquare() > 0.1 ) {
subsys.calcGrad(grad.data);
var xdir = grad.scalarMultiply(-1);
TCAD.math.lineSearch(subsys, xdir);
if (i ++ > 100) {
return;
}
}
console.log(subsys.errorSquare());
};
TCAD.math.lineSearch = function(subsys, xdir) {
var f1,f2,f3,alpha1,alpha2,alpha3,alphaStar;
var alphaMax = 1e28; //maxStep(xdir);
var x;
var x0 = new TCAD.math.Vector(subsys.params.length);
//Save initial values
TCAD.math.fillParams(subsys, x0.data);
//Start at the initial position alpha1 = 0
alpha1 = 0.;
f1 = subsys.errorSquare();
//Take a step of alpha2 = 1
alpha2 = 1.;
x = x0.add(xdir.scalarMultiply(alpha2));
TCAD.math.setParams2(subsys, x.data);
f2 = subsys.errorSquare();
//Take a step of alpha3 = 2*alpha2
alpha3 = alpha2*2;
x = x0.add(xdir.scalarMultiply(alpha3));
TCAD.math.setParams2(subsys, x.data);
f3 = subsys.errorSquare();
//Now reduce or lengthen alpha2 and alpha3 until the minimum is
//Bracketed by the triplet f1>f2<f3
while (f2 > f1 || f2 > f3) {
if (f2 > f1) {
//If f2 is greater than f1 then we shorten alpha2 and alpha3 closer to f1
//Effectively both are shortened by a factor of two.
alpha3 = alpha2;
f3 = f2;
alpha2 = alpha2 / 2;
x = x0.add( xdir.scalarMultiply(alpha2 ));
TCAD.math.setParams2(subsys, x.data);
f2 = subsys.errorSquare();
}
else if (f2 > f3) {
if (alpha3 >= alphaMax)
break;
//If f2 is greater than f3 then we increase alpha2 and alpha3 away from f1
//Effectively both are lengthened by a factor of two.
alpha2 = alpha3;
f2 = f3;
alpha3 = alpha3 * 2;
x = x0.add( xdir.scalarMultiply(alpha3));
TCAD.math.setParams2(subsys, x.data);
f3 = subsys.errorSquare();
}
}
//Get the alpha for the minimum f of the quadratic approximation
alphaStar = alpha2 + ((alpha2-alpha1)*(f1-f3))/(3*(f1-2*f2+f3));
//Guarantee that the new alphaStar is within the bracket
if (alphaStar >= alpha3 || alphaStar <= alpha1)
alphaStar = alpha2;
if (alphaStar > alphaMax)
alphaStar = alphaMax;
if (alphaStar != alphaStar)
alphaStar = 0.;
//Take a final step to alphaStar
x = x0 .add( xdir.scalarMultiply( alphaStar ) );
TCAD.math.setParams2(subsys, x.data);
return alphaStar;
};
TCAD.math.lineSearch3 = function(sys, xdir) {
var x0 = new TCAD.math.Vector(sys.params.length);
var x = new TCAD.math.Vector(sys.params.length);
TCAD.math.fillParams(sys, x0.data);
var alphas = [];
for (var i = 0; i < xdir.data.length; i++) {
alphas[i] = Number.MAX_VALUE;
}
for (var i = 0; i < sys.constraints.length; i++) {
TCAD.math.lineSearchForConstraint(sys.constraints[i], alphas, xdir, sys);
TCAD.math.setParams2(sys, x0.data);
}
for (var i = 0; i < xdir.data.length; i++) {
x.data[i][0] = xdir.data[i][0] * alphas[i] + x0.data[i][0];
}
//Take a final step to alphaStar
TCAD.math.setParams2(sys, x.data);
};
TCAD.math.lineSearchForConstraint = function(constr, alphas, _xdir, sys) {
var f1,f2,f3,alpha1,alpha2,alpha3,alphaStar;
var alphaMax = 1e28; //maxStep(xdir);
var x;
var xdir = new TCAD.math.Vector(constr.params.length);
var x0 = new TCAD.math.Vector(constr.params.length);
for (var p = 0; p < constr.params.length; p++) {
x0.data[p][0] = constr.params[p].get();
xdir.data[p][0] = _xdir.data[constr.params[p].j][0];
}
function errorSquare() {
// var t = constr.error();
// return t*t*0.5;
return sys.errorSquare();
}
function setParams2(x) {
for (var p = 0; p < constr.params.length; p++) {
constr.params[p].set(x.data[p][0]);
}
}
//Start at the initial position alpha1 = 0
alpha1 = 0.;
f1 = errorSquare();
//Take a step of alpha2 = 1
alpha2 = 1.;
x = x0.add(xdir.scalarMultiply(alpha2));
setParams2(x);
f2 = errorSquare();
//Take a step of alpha3 = 2*alpha2
alpha3 = alpha2*2;
x = x0.add(xdir.scalarMultiply(alpha3));
setParams2(x);
f3 = errorSquare();
//Now reduce or lengthen alpha2 and alpha3 until the minimum is
//Bracketed by the triplet f1>f2<f3
while (f2 > f1 || f2 > f3) {
if (f2 > f1) {
//If f2 is greater than f1 then we shorten alpha2 and alpha3 closer to f1
//Effectively both are shortened by a factor of two.
alpha3 = alpha2;
f3 = f2;
alpha2 = alpha2 / 2;
x = x0.add( xdir.scalarMultiply(alpha2 ));
setParams2(x);
f2 = errorSquare();
}
else if (f2 > f3) {
if (alpha3 >= alphaMax)
break;
//If f2 is greater than f3 then we increase alpha2 and alpha3 away from f1
//Effectively both are lengthened by a factor of two.
alpha2 = alpha3;
f2 = f3;
alpha3 = alpha3 * 2;
x = x0.add( xdir.scalarMultiply(alpha3));
setParams2(x);
f3 = errorSquare();
}
}
//Get the alpha for the minimum f of the quadratic approximation
alphaStar = alpha2 + ((alpha2-alpha1)*(f1-f3))/(3*(f1-2*f2+f3));
//Guarantee that the new alphaStar is within the bracket
if (alphaStar >= alpha3 || alphaStar <= alpha1)
alphaStar = alpha2;
if (alphaStar > alphaMax)
alphaStar = alphaMax;
if (alphaStar != alphaStar)
alphaStar = 0.;
for (var p = 0; p < constr.params.length; p++) {
var j = constr.params[p].j;
alphas[j] = Math.min(alphas[j], alphaStar);
}
return alphaStar;
};
TCAD.math.lineSearch2 = function(subsys, xdir) {
var x0 = new TCAD.math.Vector(subsys.params.length);
TCAD.math.fillParams(subsys, x0.data);
var alpha = 1.;
var f0 = subsys.errorSquare();
var x = x0.add(xdir.scalarMultiply(alpha));
TCAD.math.setParams2(subsys, x.data);
var f = subsys.errorSquare();
while (f > f0 || alpha > 0.00000001) {
alpha *= .5;
x = x0.add(xdir.scalarMultiply(alpha));
TCAD.math.setParams2(subsys, x.data);
f = subsys.errorSquare();
}
return alphaStar;
};