gusucode.com > 支持向量机工具箱 - LIBSVM OSU_SVM LS_SVM源码程序 > 支持向量机工具箱 - LIBSVM OSU_SVM LS_SVM\SVM_SteveGunn\svkernel.m
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 % '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: Steve Gunn (srg@ecs.soton.ac.uk) 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' + 1)^p1; case 'rbf' k = exp(-(u-v)*(u-v)'/(2*p1^2)); case 'erbf' k = exp(-sqrt((u-v)*(u-v)')/(2*p1^2)); case 'sigmoid' k = tanh(p1*u*v'/length(u) + 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 + (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