private static void solve_epsilon_svr(SvmProblem prob, SvmParameter param, double[] alpha, SolutionInfo si)
{
int l = prob.Lenght;
double[] alpha2 = new double[2 * l];
double[] linear_term = new double[2 * l];
sbyte[] y = new sbyte[2 * l];
int i;
for (i = 0; i < l; i++)
{
alpha2[i] = 0;
linear_term[i] = param.P - prob.Y[i];
y[i] = 1;
alpha2[i + l] = 0;
linear_term[i + l] = param.P + prob.Y[i];
y[i + l] = -1;
}
Solver s = new Solver();
s.Solve(2 * l, new SvrQ(prob, param), linear_term, y,
alpha2, param.C, param.C, param.Eps, si, param.Shrinking);
double sum_alpha = 0;
for (i = 0; i < l; i++)
{
alpha[i] = alpha2[i] - alpha2[i + l];
sum_alpha += Math.Abs(alpha[i]);
}
Svm.info("nu = " + sum_alpha / (param.C * l) + "\n");
}
protected void reconstruct_gradient()
{
// reconstruct inactive elements of G from G_bar and free variables
if (_activeSize == _length)
{
return;
}
int i, j;
int nr_free = 0;
for (j = _activeSize; j < _length; j++)
{
_g[j] = _gBar[j] + _p[j];
}
for (j = 0; j < _activeSize; j++)
{
if (is_free(j))
{
nr_free++;
}
}
if (2 * nr_free < _activeSize)
{
Svm.info("\nWARNING: using -h 0 may be faster\n");
}
if (nr_free * _length > 2 * _activeSize * (_length - _activeSize))
{
for (i = _activeSize; i < _length; i++)
{
double[] Q_i = _q.GetQ(i, _activeSize);
for (j = 0; j < _activeSize; j++)
{
if (is_free(j))
{
_g[i] += _alpha[j] * Q_i[j];
}
}
}
}
else
{
for (i = 0; i < _activeSize; i++)
{
if (is_free(i))
{
double[] Q_i = _q.GetQ(i, _length);
double alpha_i = _alpha[i];
for (j = _activeSize; j < _length; j++)
{
_g[j] += alpha_i * Q_i[j];
}
}
}
}
}
//from Svm.svm_predict_probability
public double PredictProbability(SvmNode[] x, double[] prob_estimates)
{
if (!SvmType.IsSVC() || ProbA == null || ProbB == null)
{
return(Predict(x));
}
int nr_class = NrClass;
double[] dec_values = new double[nr_class * (nr_class - 1) / 2];
PredictValues(x, dec_values);
double min_prob = 1e-7;
double[][] pairwise_prob = new double[nr_class][];
for (int i = 0; i < nr_class; i++)
{
pairwise_prob[i] = new double[nr_class];
}
int k = 0;
for (int i = 0; i < nr_class; i++)
{
for (int j = i + 1; j < nr_class; j++)
{
pairwise_prob[i][j] = Math.Min(Math.Max(Svm.sigmoid_predict(dec_values[k], ProbA[k], ProbB[k]), min_prob), 1 - min_prob);
pairwise_prob[j][i] = 1 - pairwise_prob[i][j];
k++;
}
}
Svm.multiclass_probability(nr_class, pairwise_prob, prob_estimates);
int prob_max_idx = 0;
for (int i = 1; i < nr_class; i++)
{
if (prob_estimates[i] > prob_estimates[prob_max_idx])
{
prob_max_idx = i;
}
}
return(Label[prob_max_idx]);
}
private static void solve_c_svc(SvmProblem prob, SvmParameter param, double[] alpha, SolutionInfo si, double Cp, double Cn)
{
int l = prob.Lenght;
double[] minus_ones = new double[l];
sbyte[] y = new sbyte[l];
for (int i = 0; i < l; i++)
{
alpha[i] = 0;
minus_ones[i] = -1;
if (prob.Y[i] > 0)
{
y[i] = +1;
}
else
{
y[i] = -1;
}
}
Solver s = new Solver();
s.Solve(l, new SvcQ(prob, param, y), minus_ones, y,
alpha, Cp, Cn, param.Eps, si, param.Shrinking);
double sum_alpha = 0;
for (int i = 0; i < l; i++)
{
sum_alpha += alpha[i];
}
if (Cp == Cn)
{
Svm.info("nu = " + sum_alpha / (Cp * prob.Lenght) + "\n");
}
for (int i = 0; i < l; i++)
{
alpha[i] *= y[i];
}
}
// Return parameter of a Laplace distribution
private static double svm_svr_probability(SvmProblem prob, SvmParameter param)
{
int i;
int nr_fold = 5;
double[] ymv = new double[prob.Lenght];
double mae = 0;
var newparam = (SvmParameter)param.Clone();
newparam.Probability = false;
CrossValidation(prob, newparam, nr_fold, ymv);
for (i = 0; i < prob.Lenght; i++)
{
ymv[i] = prob.Y[i] - ymv[i];
mae += Math.Abs(ymv[i]);
}
mae /= prob.Lenght;
double std = Math.Sqrt(2 * mae * mae);
int count = 0;
mae = 0;
for (i = 0; i < prob.Lenght; i++)
{
if (Math.Abs(ymv[i]) > 5 * std)
{
count = count + 1;
}
else
{
mae += Math.Abs(ymv[i]);
}
}
mae /= (prob.Lenght - count);
Svm.info("Prob. model for test data: target value = predicted value + z,\nz: Laplace distribution e^(-|z|/sigma)/(2sigma),sigma=" + mae + "\n");
return(mae);
}
private static void solve_nu_svr(SvmProblem prob, SvmParameter param, double[] alpha, SolutionInfo si)
{
int l = prob.Lenght;
double C = param.C;
double[] alpha2 = new double[2 * l];
double[] linear_term = new double[2 * l];
sbyte[] y = new sbyte[2 * l];
int i;
double sum = C * param.Nu * l / 2;
for (i = 0; i < l; i++)
{
alpha2[i] = alpha2[i + l] = Math.Min(sum, C);
sum -= alpha2[i];
linear_term[i] = -prob.Y[i];
y[i] = 1;
linear_term[i + l] = prob.Y[i];
y[i + l] = -1;
}
var s = new SolverNu();
s.Solve(2 * l, new SvrQ(prob, param), linear_term, y,
alpha2, C, C, param.Eps, si, param.Shrinking);
Svm.info("epsilon = " + (-si.R) + "\n");
for (i = 0; i < l; i++)
{
alpha[i] = alpha2[i] - alpha2[i + l];
}
}
public virtual void Solve(int length, QMatrix Q, double[] p_, sbyte[] y_,
double[] alpha_, double Cp, double Cn, double eps, SolutionInfo si, bool shrinking)
{
this._length = length;
this._q = Q;
_qd = Q.GetQD();
_p = (double[])p_.Clone();
_y = (sbyte[])y_.Clone();
_alpha = (double[])alpha_.Clone();
this._cp = Cp;
this._cn = Cn;
this._eps = eps;
this._unshrink = false;
// initialize alpha_status
{
_alphaStatus = new BoundType[length];
for (int i = 0; i < length; i++)
{
UpdateAlphaStatus(i);
}
}
// initialize active set (for shrinking)
{
_activeSet = new int[length];
for (int i = 0; i < length; i++)
{
_activeSet[i] = i;
}
_activeSize = length;
}
// initialize gradient
{
_g = new double[length];
_gBar = new double[length];
int i;
for (i = 0; i < length; i++)
{
_g[i] = _p[i];
_gBar[i] = 0;
}
for (i = 0; i < length; i++)
{
if (!is_lower_bound(i))
{
double[] Q_i = Q.GetQ(i, length);
double alpha_i = _alpha[i];
int j;
for (j = 0; j < length; j++)
{
_g[j] += alpha_i * Q_i[j];
}
if (is_upper_bound(i))
{
for (j = 0; j < length; j++)
{
_gBar[j] += GetC(i) * Q_i[j];
}
}
}
}
}
// optimization step
int iter = 0;
int max_iter = Math.Max(10000000, length > int.MaxValue / 100 ? int.MaxValue : 100 * length);
int counter = Math.Min(length, 1000) + 1;
int[] working_set = new int[2];
while (iter < max_iter)
{
// show progress and do shrinking
if (--counter == 0)
{
counter = Math.Min(length, 1000);
if (shrinking)
{
do_shrinking();
}
Svm.info(".");
}
if (select_working_set(working_set) != 0)
{
// reconstruct the whole gradient
reconstruct_gradient();
// reset active set size and check
_activeSize = length;
Svm.info("*");
if (select_working_set(working_set) != 0)
{
break;
}
else
{
counter = 1; // do shrinking next iteration
}
}
int i = working_set[0];
int j = working_set[1];
++iter;
// update alpha[i] and alpha[j], handle bounds carefully
double[] Q_i = Q.GetQ(i, _activeSize);
double[] Q_j = Q.GetQ(j, _activeSize);
double C_i = GetC(i);
double C_j = GetC(j);
double old_alpha_i = _alpha[i];
double old_alpha_j = _alpha[j];
if (_y[i] != _y[j])
{
double quad_coef = _qd[i] + _qd[j] + 2 * Q_i[j];
if (quad_coef <= 0)
{
quad_coef = 1e-12;
}
double delta = (-_g[i] - _g[j]) / quad_coef;
double diff = _alpha[i] - _alpha[j];
_alpha[i] += delta;
_alpha[j] += delta;
if (diff > 0)
{
if (_alpha[j] < 0)
{
_alpha[j] = 0;
_alpha[i] = diff;
}
}
else
{
if (_alpha[i] < 0)
{
_alpha[i] = 0;
_alpha[j] = -diff;
}
}
if (diff > C_i - C_j)
{
if (_alpha[i] > C_i)
{
_alpha[i] = C_i;
_alpha[j] = C_i - diff;
}
}
else
{
if (_alpha[j] > C_j)
{
_alpha[j] = C_j;
_alpha[i] = C_j + diff;
}
}
}
else
{
double quad_coef = _qd[i] + _qd[j] - 2 * Q_i[j];
if (quad_coef <= 0)
{
quad_coef = 1e-12;
}
double delta = (_g[i] - _g[j]) / quad_coef;
double sum = _alpha[i] + _alpha[j];
_alpha[i] -= delta;
_alpha[j] += delta;
if (sum > C_i)
{
if (_alpha[i] > C_i)
{
_alpha[i] = C_i;
_alpha[j] = sum - C_i;
}
}
else
{
if (_alpha[j] < 0)
{
_alpha[j] = 0;
_alpha[i] = sum;
}
}
if (sum > C_j)
{
if (_alpha[j] > C_j)
{
_alpha[j] = C_j;
_alpha[i] = sum - C_j;
}
}
else
{
if (_alpha[i] < 0)
{
_alpha[i] = 0;
_alpha[j] = sum;
}
}
}
// update G
double delta_alpha_i = _alpha[i] - old_alpha_i;
double delta_alpha_j = _alpha[j] - old_alpha_j;
for (int k = 0; k < _activeSize; k++)
{
_g[k] += Q_i[k] * delta_alpha_i + Q_j[k] * delta_alpha_j;
}
// update alpha_status and G_bar
bool ui = is_upper_bound(i);
bool uj = is_upper_bound(j);
UpdateAlphaStatus(i);
UpdateAlphaStatus(j);
//int k;
if (ui != is_upper_bound(i))
{
Q_i = Q.GetQ(i, length);
if (ui)
{
for (int k = 0; k < length; k++)
{
_gBar[k] -= C_i * Q_i[k];
}
}
else
{
for (int k = 0; k < length; k++)
{
_gBar[k] += C_i * Q_i[k];
}
}
}
if (uj != is_upper_bound(j))
{
Q_j = Q.GetQ(j, length);
if (uj)
{
for (int k = 0; k < length; k++)
{
_gBar[k] -= C_j * Q_j[k];
}
}
else
{
for (int k = 0; k < length; k++)
{
_gBar[k] += C_j * Q_j[k];
}
}
}
}
if (iter >= max_iter)
{
if (_activeSize < length)
{
// reconstruct the whole gradient to calculate objective value
reconstruct_gradient();
_activeSize = length;
Svm.info("*");
}
Svm.info("\nWARNING: reaching max number of iterations");
}
// calculate rho
si.Rho = calculate_rho();
// calculate objective value
double v = 0;
for (int i = 0; i < length; i++)
{
v += _alpha[i] * (_g[i] + _p[i]);
}
si.Obj = v / 2;
// put back the solution
for (int i = 0; i < length; i++)
{
alpha_[_activeSet[i]] = _alpha[i];
}
si.UpperBoundP = Cp;
si.UpperBoundN = Cn;
Svm.info("\noptimization finished, #iter = " + iter + "\n");
}
//
// Interface functions
//
public static SvmModel Train(SvmProblem prob, SvmParameter param)
{
var model = new SvmModel();
model.Param = param;
if (param.SvmType.IsSVROrOneClass())
{
// regression or one-class-svm
model.NrClass = 2;
model.Label = null;
model.SupportVectorsNumbers = null;
model.ProbA = null; model.ProbB = null;
model.SupportVectorsCoefficients = new double[1][];
if (param.Probability && param.SvmType.IsSVR())
{
model.ProbA = new double[1];
model.ProbA[0] = svm_svr_probability(prob, param);
}
DecisionFunction f = svm_train_one(prob, param, 0, 0);
model.Rho = new double[1];
model.Rho[0] = f.Rho;
int nSV = 0;
int i;
for (i = 0; i < prob.Lenght; i++)
{
if (Math.Abs(f.Alpha[i]) > 0)
{
++nSV;
}
}
model.TotalSupportVectorsNumber = nSV;
model.SupportVectors = new SvmNode[nSV][];
model.SupportVectorsCoefficients[0] = new double[nSV];
int j = 0;
for (i = 0; i < prob.Lenght; i++)
{
if (Math.Abs(f.Alpha[i]) > 0)
{
model.SupportVectors[j] = prob.X[i];
model.SupportVectorsCoefficients[0][j] = f.Alpha[i];
++j;
}
}
}
else
{
// classification
int l = prob.Lenght;
int[] perm = new int[l];
int nr_class;
int[] label;
int[] start;
int[] count;
// group training data of the same class
svm_group_classes(prob, out nr_class, out label, out start, out count, perm);
if (nr_class == 1)
{
Svm.info("WARNING: training data in only one class. See README for details.\n");
}
SvmNode[][] x = new SvmNode[l][];
int i;
for (i = 0; i < l; i++)
{
x[i] = prob.X[perm[i]];
}
// calculate weighted C
double[] weighted_C = new double[nr_class];
for (i = 0; i < nr_class; i++)
{
weighted_C[i] = param.C;
}
for (i = 0; i < param.WeightsCount; i++)
{
int j;
for (j = 0; j < nr_class; j++)
{
if (param.WeightLabel[i] == label[j])
{
break;
}
}
if (j == nr_class)
{
System.Diagnostics.Debug.WriteLine("WARNING: class label " + param.WeightLabel[i] + " specified in weight is not found\n");
}
else
{
weighted_C[j] *= param.Weight[i];
}
}
// train k*(k-1)/2 models
var nonzero = new bool[l];
for (i = 0; i < l; i++)
{
nonzero[i] = false;
}
var f = new DecisionFunction[nr_class * (nr_class - 1) / 2];
double[] probA = null, probB = null;
if (param.Probability)
{
probA = new double[nr_class * (nr_class - 1) / 2];
probB = new double[nr_class * (nr_class - 1) / 2];
}
int p = 0;
for (i = 0; i < nr_class; i++)
{
for (int j = i + 1; j < nr_class; j++)
{
int si = start[i], sj = start[j];
int ci = count[i], cj = count[j];
var subprobLenght = ci + cj;
var sub_prob = new SvmProblem
{
X = new SvmNode[subprobLenght][],
Y = new double[subprobLenght]
};
int k;
for (k = 0; k < ci; k++)
{
sub_prob.X[k] = x[si + k];
sub_prob.Y[k] = +1;
}
for (k = 0; k < cj; k++)
{
sub_prob.X[ci + k] = x[sj + k];
sub_prob.Y[ci + k] = -1;
}
if (param.Probability)
{
double[] probAB = new double[2];
svm_binary_svc_probability(sub_prob, param, weighted_C[i], weighted_C[j], probAB);
probA[p] = probAB[0];
probB[p] = probAB[1];
}
f[p] = svm_train_one(sub_prob, param, weighted_C[i], weighted_C[j]);
for (k = 0; k < ci; k++)
{
if (!nonzero[si + k] && Math.Abs(f[p].Alpha[k]) > 0)
{
nonzero[si + k] = true;
}
}
for (k = 0; k < cj; k++)
{
if (!nonzero[sj + k] && Math.Abs(f[p].Alpha[ci + k]) > 0)
{
nonzero[sj + k] = true;
}
}
++p;
}
}
// build output
model.NrClass = nr_class;
model.Label = new int[nr_class];
for (i = 0; i < nr_class; i++)
{
model.Label[i] = label[i];
}
model.Rho = new double[nr_class * (nr_class - 1) / 2];
for (i = 0; i < nr_class * (nr_class - 1) / 2; i++)
{
model.Rho[i] = f[i].Rho;
}
if (param.Probability)
{
model.ProbA = new double[nr_class * (nr_class - 1) / 2];
model.ProbB = new double[nr_class * (nr_class - 1) / 2];
for (i = 0; i < nr_class * (nr_class - 1) / 2; i++)
{
model.ProbA[i] = probA[i];
model.ProbB[i] = probB[i];
}
}
else
{
model.ProbA = null;
model.ProbB = null;
}
int nnz = 0;
int[] nz_count = new int[nr_class];
model.SupportVectorsNumbers = new int[nr_class];
for (i = 0; i < nr_class; i++)
{
int nSV = 0;
for (int j = 0; j < count[i]; j++)
{
if (nonzero[start[i] + j])
{
++nSV;
++nnz;
}
}
model.SupportVectorsNumbers[i] = nSV;
nz_count[i] = nSV;
}
Svm.info("Total nSV = " + nnz + "\n");
model.TotalSupportVectorsNumber = nnz;
model.SupportVectors = new SvmNode[nnz][];
p = 0;
for (i = 0; i < l; i++)
{
if (nonzero[i])
{
model.SupportVectors[p++] = x[i];
}
}
int[] nz_start = new int[nr_class];
nz_start[0] = 0;
for (i = 1; i < nr_class; i++)
{
nz_start[i] = nz_start[i - 1] + nz_count[i - 1];
}
model.SupportVectorsCoefficients = new double[nr_class - 1][];
for (i = 0; i < nr_class - 1; i++)
{
model.SupportVectorsCoefficients[i] = new double[nnz];
}
p = 0;
for (i = 0; i < nr_class; i++)
{
for (int j = i + 1; j < nr_class; j++)
{
// classifier (i,j): coefficients with
// i are in sv_coef[j-1][nz_start[i]...],
// j are in sv_coef[i][nz_start[j]...]
int si = start[i];
int sj = start[j];
int ci = count[i];
int cj = count[j];
int q = nz_start[i];
int k;
for (k = 0; k < ci; k++)
{
if (nonzero[si + k])
{
model.SupportVectorsCoefficients[j - 1][q++] = f[p].Alpha[k];
}
}
q = nz_start[j];
for (k = 0; k < cj; k++)
{
if (nonzero[sj + k])
{
model.SupportVectorsCoefficients[i][q++] = f[p].Alpha[ci + k];
}
}
++p;
}
}
}
return(model);
}
private static void solve_nu_svc(SvmProblem prob, SvmParameter param, double[] alpha, SolutionInfo si)
{
int i;
int l = prob.Lenght;
double nu = param.Nu;
sbyte[] y = new sbyte[l];
for (i = 0; i < l; i++)
{
if (prob.Y[i] > 0)
{
y[i] = +1;
}
else
{
y[i] = -1;
}
}
double sum_pos = nu * l / 2;
double sum_neg = nu * l / 2;
for (i = 0; i < l; i++)
{
if (y[i] == +1)
{
alpha[i] = Math.Min(1.0, sum_pos);
sum_pos -= alpha[i];
}
else
{
alpha[i] = Math.Min(1.0, sum_neg);
sum_neg -= alpha[i];
}
}
double[] zeros = new double[l];
for (i = 0; i < l; i++)
{
zeros[i] = 0;
}
var s = new SolverNu();
s.Solve(l, new SvcQ(prob, param, y), zeros, y,
alpha, 1.0, 1.0, param.Eps, si, param.Shrinking);
double r = si.R;
Svm.info("C = " + 1 / r + "\n");
for (i = 0; i < l; i++)
{
alpha[i] *= y[i] / r;
}
si.Rho /= r;
si.Obj /= (r * r);
si.UpperBoundP = 1 / r;
si.UpperBoundN = 1 / r;
}
// Method 2 from the multiclass_prob paper by Wu, Lin, and Weng
internal static void multiclass_probability(int k, double[][] r, double[] p)
{
int t, j;
int iter = 0, max_iter = Math.Max(100, k);
//double[][] Q = new double[k][k];
double[][] Q = new double[k][];
for (int i = 0; i < k; i++)
{
Q[i] = new double[k];
}
double[] Qp = new double[k];
double pQp, eps = 0.005 / k;
for (t = 0; t < k; t++)
{
p[t] = 1.0 / k; // Valid if k = 1
Q[t][t] = 0;
for (j = 0; j < t; j++)
{
Q[t][t] += r[j][t] * r[j][t];
Q[t][j] = Q[j][t];
}
for (j = t + 1; j < k; j++)
{
Q[t][t] += r[j][t] * r[j][t];
Q[t][j] = -r[j][t] * r[t][j];
}
}
for (iter = 0; iter < max_iter; iter++)
{
// stopping condition, recalculate QP,pQP for numerical accuracy
pQp = 0;
for (t = 0; t < k; t++)
{
Qp[t] = 0;
for (j = 0; j < k; j++)
{
Qp[t] += Q[t][j] * p[j];
}
pQp += p[t] * Qp[t];
}
double max_error = 0;
for (t = 0; t < k; t++)
{
double error = Math.Abs(Qp[t] - pQp);
if (error > max_error)
{
max_error = error;
}
}
if (max_error < eps)
{
break;
}
for (t = 0; t < k; t++)
{
double diff = (-Qp[t] + pQp) / Q[t][t];
p[t] += diff;
pQp = (pQp + diff * (diff * Q[t][t] + 2 * Qp[t])) / (1 + diff) / (1 + diff);
for (j = 0; j < k; j++)
{
Qp[j] = (Qp[j] + diff * Q[t][j]) / (1 + diff);
p[j] /= (1 + diff);
}
}
}
if (iter >= max_iter)
{
Svm.info("Exceeds max_iter in multiclass_prob\n");
}
}
// Platt's binary SVM Probablistic Output: an improvement from Lin et al.
private static void sigmoid_train(int l, double[] dec_values, double[] labels, double[] probAB)
{
//double A, B;
double prior1 = 0, prior0 = 0;
//int i;
for (int i = 0; i < l; i++)
{
if (labels[i] > 0)
{
prior1 += 1;
}
else
{
prior0 += 1;
}
}
const int max_iter = 100; // Maximal number of iterations
const double min_step = 1e-10; // Minimal step taken in line search
const double sigma = 1e-12; // For numerically strict PD of Hessian
const double eps = 1e-5;
double hiTarget = (prior1 + 1.0) / (prior1 + 2.0);
double loTarget = 1 / (prior0 + 2.0);
double[] t = new double[l];
double fApB;
int iter;
// Initial Point and Initial Fun Value
double A = 0.0;
double B = Math.Log((prior0 + 1.0) / (prior1 + 1.0));
double fval = 0.0;
for (int i = 0; i < l; i++)
{
if (labels[i] > 0)
{
t[i] = hiTarget;
}
else
{
t[i] = loTarget;
}
fApB = dec_values[i] * A + B;
if (fApB >= 0)
{
fval += t[i] * fApB + Math.Log(1 + Math.Exp(-fApB));
}
else
{
fval += (t[i] - 1) * fApB + Math.Log(1 + Math.Exp(fApB));
}
}
for (iter = 0; iter < max_iter; iter++)
{
// Update Gradient and Hessian (use H' = H + sigma I)
double h11 = sigma; // numerically ensures strict PD
double h22 = sigma;
double h21 = 0.0;
double g1 = 0.0;
double g2 = 0.0;
for (int i = 0; i < l; i++)
{
double p, q;
fApB = dec_values[i] * A + B;
if (fApB >= 0)
{
p = Math.Exp(-fApB) / (1.0 + Math.Exp(-fApB));
q = 1.0 / (1.0 + Math.Exp(-fApB));
}
else
{
p = 1.0 / (1.0 + Math.Exp(fApB));
q = Math.Exp(fApB) / (1.0 + Math.Exp(fApB));
}
double d2 = p * q;
h11 += dec_values[i] * dec_values[i] * d2;
h22 += d2;
h21 += dec_values[i] * d2;
double d1 = t[i] - p;
g1 += dec_values[i] * d1;
g2 += d1;
}
// Stopping Criteria
if (Math.Abs(g1) < eps && Math.Abs(g2) < eps)
{
break;
}
// Finding Newton direction: -inv(H') * g
double det = h11 * h22 - h21 * h21;
double dA = -(h22 * g1 - h21 * g2) / det;
double dB = -(-h21 * g1 + h11 * g2) / det;
double gd = g1 * dA + g2 * dB;
double stepsize = 1; // Line Search
while (stepsize >= min_step)
{
double newA = A + stepsize * dA;
double newB = B + stepsize * dB;
// New function value
double newf = 0.0;
for (int i = 0; i < l; i++)
{
fApB = dec_values[i] * newA + newB;
if (fApB >= 0)
{
newf += t[i] * fApB + Math.Log(1 + Math.Exp(-fApB));
}
else
{
newf += (t[i] - 1) * fApB + Math.Log(1 + Math.Exp(fApB));
}
}
// Check sufficient decrease
if (newf < fval + 0.0001 * stepsize * gd)
{
A = newA; B = newB; fval = newf;
break;
}
else
{
stepsize = stepsize / 2.0;
}
}
if (stepsize < min_step)
{
Svm.info("Line search fails in two-class probability estimates\n");
break;
}
}
if (iter >= max_iter)
{
Svm.info("Reaching maximal iterations in two-class probability estimates\n");
}
probAB[0] = A; probAB[1] = B;
}
private static DecisionFunction svm_train_one(SvmProblem prob, SvmParameter param, double Cp, double Cn)
{
double[] alpha = new double[prob.Lenght];
var si = new SolutionInfo();
switch (param.SvmType)
{
case SvmType.C_SVC:
solve_c_svc(prob, param, alpha, si, Cp, Cn);
break;
case SvmType.NU_SVC:
solve_nu_svc(prob, param, alpha, si);
break;
case SvmType.ONE_CLASS:
solve_one_class(prob, param, alpha, si);
break;
case SvmType.EPSILON_SVR:
solve_epsilon_svr(prob, param, alpha, si);
break;
case SvmType.NU_SVR:
solve_nu_svr(prob, param, alpha, si);
break;
}
Svm.info("obj = " + si.Obj + ", rho = " + si.Rho + "\n");
// output SVs
int nSV = 0;
int nBSV = 0;
for (int i = 0; i < prob.Lenght; i++)
{
if (Math.Abs(alpha[i]) > 0)
{
++nSV;
if (prob.Y[i] > 0)
{
if (Math.Abs(alpha[i]) >= si.UpperBoundP)
{
++nBSV;
}
}
else
{
if (Math.Abs(alpha[i]) >= si.UpperBoundN)
{
++nBSV;
}
}
}
}
Svm.info("nSV = " + nSV + ", nBSV = " + nBSV + "\n");
var f = new DecisionFunction(alpha, si.Rho);
return(f);
}