svkernel.asv

支持向量机 这是我的老师编写的matlab源文件 希望对大家有用

function k = svkernel(ker,u,v)
%SVKERNEL kernel for Support Vector Methods
%
%  Usage: k = svkernel(ker,u,v)
%
%  Parameters: ker - kernel type
%              u,v - kernel arguments
%
%  Values for ker: 'linear'  -
%                  'poly'    - p1 is degree of polynomial
%                  'sa'      - p1 is scale
%                  'rbf'     - p1 is width of rbfs (sigma)
%                  'sigmoid' - p1 is scale, p2 is offset
%                  'spline'  -
%                  'bspline' - p1 is degree of bspline
%                  'fourier' - p1 is degree
%                  'erfb'    - p1 is width of rbfs (sigma)
%                  'anova'   - p1 is max order of terms
%              
%  Author: Zhou Weida ([e-mail])

  if (nargin < 1) % check correct number of arguments
     help svkernel
  else
     
    global p1 p2;

    % could check for correct number of args in here
    % but will slow things down further
    switch lower(ker)
      case 'linear'
        k = u*v';
      case 'poly'
         k = (u*v')^p1;
      case 'comrbf'
         k = exp(-((real(u)-real(v))*(real(u)-real(v))'...
            +(imag(u)-imag(v))*(imag(u)-imag(v))')/(2*p1^2));
      case 'rbf'
         k = exp(-(u-v)*(u-v)'/(2*p1^2));
      case 'sa'
         if sum(u-v)==0
            k=1;
         else
            k =(sin(p1*sum(u-v)))./(p1*sum(u-v));
         end
         
      case '1_wavelet'
         k=0;
         for i=1:1:4
            k=k+cos(1.75*u/(p1*2^(-1*i)))*cos(1.75*v/(p1*2^(-1*i)))*exp(-(u'*u+v'*v)/(2*p1*p1*2^(-2*i)));
         end
         
      case 'erbf'
        k = exp(-sqrt((u-v)*(u-v)')/(2*p1^2));
      case 'sigmoid'
         %k = tanh(p1*u*v'/length(u) + p2);
         k = tanh(p1*u*v' + p2);
      case 'fourier'
        z = sin(p1 + 1/2)*2*ones(length(u),1);
        i = find(u-v);
        z(i) = sin(p1 + 1/2)*(u(i)-v(i))./sin((u(i)-v(i))/2);
        k = prod(z);
      case 'spline'
        z = 1 + u.*v + u.*v.*min(u,v) - ((u+v)/2).*(min(u,v)).^2 + (1/3)*(min(u,v)).^3;
        k = prod(z);
      case {'curvspline','anova'}
        z = 1 + u.*v + (1/2)*u.*v.*min(u,v) - (1/6)*(min(u,v)).^3;
        k = prod(z);
        case 'gammapdf'
            k=1;
            if (isempty(u<0) & isempty(v<=0))
                for k1=1:length (v)
                    alpha=v(1,k1)*v(1,k1)/(p1*p1)-1;
                    beta=(p1*p1)/v(1,k1);
                    k=k*u(1,k1).^alpha*exp(-u(1,k1)/beta)/(beta.^(alpha+1)*gamma(alpha+1));
                end
            else
                k=0;
            end
        case 'betapdf'
            k=1;
            if (isempty(u<=0) & isempty(u>=1) & isempty(v<=0) & isempty(v>=1))
                for k1=1:length(v)
                    temp=v(1,k1)-v(1,k1)*v(1,k1)-p1*p1
                    alpha=v(1,k1)*temp/(p1*p1)-1;
                    beta=(1-v(1,k1))*temp/(p1*p1)-1;
                    k=k*gamma(
                
                
            
            

% - sum(u.*v) - 1; 
%        z = 1 + u.*v + (1/2)*u.*v.*min(u,v) - (1/6)*(min(u,v)).^3;
%        k = prod(z); 
%        z = (1/2)*u.*v.*min(u,v) - (1/6)*(min(u,v)).^3;
%        k = prod(z); 

      case 'bspline'
        z = 0;
        for r = 0: 2*(p1+1)
          z = z + (-1)^r*binomial(2*(p1+1),r)*(max(0,u-v + p1+1 - r)).^(2*p1 + 1);
        end
        k = prod(z);
      case 'anovaspline1'
        z = 1 + u.*v + u.*v.*min(u,v) - ((u+v)/2).*(min(u,v)).^2 + (1/3)*(min(u,v)).^3;
        k = prod(z); 
      case 'anovaspline2'
        z = 1 + u.*v + (u.*v).^2 + (u.*v).^2.*min(u,v) - u.*v.*(u+v).*(min(u,v)).^2 + (1/3)*(u.^2 + 4*u.*v + v.^2).*(min(u,v)).^3 - (1/2)*(u+v).*(min(u,v)).^4 + (1/5)*(min(u,v)).^5;
        k = prod(z);
      case 'anovaspline3'
        z = 1 + u.*v + (u.*v).^2 + (u.*v).^3 + (u.*v).^3.*min(u,v) - (3/2)*(u.*v).^2.*(u+v).*(min(u,v)).^2 + u.*v.*(u.^2 + 3*u.*v + v.^2).*(min(u,v)).^3 - (1/4)*(u.^3 + 9*u.^2.*v + 9*u.*v.^2 + v.^3).*(min(u,v)).^4 + (3/5)*(u.^2 + 3*u.*v + v.^2).*(min(u,v)).^5 - (1/2)*(u+v).*(min(u,v)).^6 + (1/7)*(min(u,v)).^7;
        k = prod(z);
      case 'anovabspline'
        z = 0;
        for r = 0: 2*(p1+1)
          z = z + (-1)^r*binomial(2*(p1+1),r)*(max(0,u-v + p1+1 - r)).^(2*p1 + 1);
        end
        k = prod(1 + z);
      otherwise
        k = u*v';
    end

  end