拟牛顿法.docx
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拟牛顿法
拟牛顿法(变尺度法)DFP算法的c/c++源码
#include"iostream.h"
#include"math.h"
voidcomput_grad(double(*pf)(double*x),intn,double*point,double*grad);//计算梯度
doubleline_search1(double(*pf)(double*x),intn,double*start,double*direction);//0.618法线搜索
doubleline_search(double(*pf)(double*x),intn,double*start,double*direction);//解析法线搜索
doubleDFP(double(*pf)(double*x),intn,double*min_point);//无约束变尺度法
//梯度计算模块
//参数:
指向目标函数的指针,变量个数,求梯度的点,结果
voidcomput_grad(double(*pf)(double*x),
intn,
double*point,
double*grad)
{
doubleh=1E-3;
inti;
double*temp;
temp=newdouble[n];
for(i=1;i<=n;i++)
{
temp[i-1]=point[i-1];
}
for(i=1;i<=n;i++)
{
temp[i-1]+=0.5*h;
grad[i-1]=4*pf(temp)/(3*h);
temp[i-1]-=h;
grad[i-1]-=4*pf(temp)/(3*h);
temp[i-1]+=(3*h/2);
grad[i-1]-=(pf(temp)/(6*h));
temp[i-1]-=(2*h);
grad[i-1]+=(pf(temp)/(6*h));
temp[i-1]=point[i-1];
}
delete[]temp;
}
//一维搜索模块
//参数:
指向目标函数的指针,变量个数,出发点,搜索方向
//返回:
最优步长
doubleline_search(
double(*pf)(double*x),
intn,
double*start,
double*direction)
{
inti;
doublestep=0.001;
doublea=0,value_a,diver_a;
doubleb,value_b,diver_b;
doublet,value_t,diver_t;
doubles,z,w;
double*grad,*temp_point;
grad=newdouble[n];
temp_point=newdouble[n];
comput_grad(pf,n,start,grad);
diver_a=0;
for(i=1;i<=n;i++)
diver_a=diver_a+grad[i-1]*direction[i-1];
do
{
b=a+step;
for(i=1;i<=n;i++)
temp_point[i-1]=start[i-1]+b*direction[i-1];
comput_grad(pf,n,temp_point,grad);
diver_b=0;
for(i=1;i<=n;i++)
diver_b=diver_b+grad[i-1]*direction[i-1];
if(fabs(diver_b)<1E-10)
{
delete[]grad;
delete[]temp_point;
return(b);
}
if(diver_b<-1E-15)
{
a=b;
diver_a=diver_b;
step=2*step;
}
}while(diver_b<=1E-15);
for(i=1;i<=n;i++)
temp_point[i-1]=start[i-1]+a*direction[i-1];
value_a=(*pf)(temp_point);
for(i=1;i<=n;i++)
temp_point[i-1]=start[i-1]+b*direction[i-1];
value_b=(*pf)(temp_point);
do
{
s=3*(value_b-value_a)/(b-a);
z=s-diver_a-diver_b;
w=sqrt(fabs(z*z-diver_a*diver_b));//////////////////!
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t=a+(w-z-diver_a)*(b-a)/(diver_b-diver_a+2*w);
value_b=(*pf)(temp_point);
for(i=1;i<=n;i++)
temp_point[i-1]=start[i-1]+t*direction[i-1];
value_t=(*pf)(temp_point);
comput_grad(pf,n,temp_point,grad);
diver_t=0;
for(i=1;i<=n;i++)
diver_t=diver_t+grad[i-1]*direction[i-1];
if(diver_t>1E-6)
{
b=t;
value_b=value_t;
diver_b=diver_t;
}
elseif(diver_t<-1E-6)
{
a=t;
value_a=value_t;
diver_a=diver_t;
}
elsebreak;
}while((fabs(diver_t)>=1E-6)&&(fabs(b-a)>1E-6));
delete[]grad;
delete[]temp_point;
return(t);
}
//无约束变尺度法DFP函数声明
//
//参数:
pf指向目标函数的指针,n变量个数,min_point接受初始点、存放结果
//返回:
极小点处函数值
//
doubleDFP(
double(*pf)(double*x),
intn,
double*min_point
)
{
inti,j;
intk=0;
doublee=1E-5;
doubleg_norm;
double*g0=newdouble[n];//梯度
double*g1=newdouble[n];
double*dg=newdouble[n];
double*p=newdouble[n];//搜索方向=-g
doublet;//一维搜索步长
double*x0=newdouble[n];
double*x1=newdouble[n];
double*dx=newdouble[n];
double**H=newdouble*[n];
for(i=0;idouble**tempH=newdouble*[n];
for(i=0;idouble*gH=newdouble[n];
double*Hg=newdouble[n];
doublenum1;
doublenum2;
for(i=0;ifor(j=0;j{
if(i==j)H[i][j]=1.0;//H0=I
elseH[i][j]=0.0;
tempH[i][j]=0.0;
}
for(i=0;ix0[i]=min_point[i];
comput_grad(pf,n,x0,g0);
g_norm=0.0;
for(i=0;ig_norm=sqrt(g_norm);
if(g_norm{
for(i=0;idelete[]g0;
delete[]g1;
delete[]dg;
delete[]p;
delete[]x0;
delete[]x1;
delete[]dx;
for(i=0;idelete[]H;
for(i=0;idelete[]tempH;
delete[]gH;
delete[]Hg;
returnpf(min_point);
}
for(i=0;ido
{
t=line_search(pf,n,x0,p);
for(i=0;icomput_grad(pf,n,x1,g1);
g_norm=0.0;
for(i=0;ig_norm=sqrt(g_norm);
//cout<if(g_norm{
for(i=0;idelete[]g0;
delete[]g1;
delete[]dg;
delete[]p;
delete[]x0;
delete[]x1;
delete[]dx;
for(i=0;idelete[]H;
for(i=0;idelete[]tempH;
delete[]gH;
delete[]Hg;
returnpf(min_point);
}
for(i=0;i{
dx[i]=x1[i]-x0[i];
dg[i]=g1[i]-g0[i];
}
//////////////////求Hk+1的矩阵运算
//g*H,H*g
for(i=0;i{
gH[i]=0.0;
Hg[i]=0.0;
}
for(i=0;i{
for(j=0;j{
gH[i]=gH[i]+dg[j]*H[j][i];
//Hg[i]=Hg[i]+H[i][j]*dg[j];
Hg[i]=gH[i];
}
}
//num1,num2
num1=0.0;
num2=0.0;
for(i=0;i{
num1=num1+dx[i]*dg[i];
num2=num2+gH[i]*dg[i];
}
//tempH[i][j]
for(i=0;ifor(j=0;jtempH[i][j]=0.0;
for(i=0;i{
for(j=0;j{
tempH[i][j]=tempH[i][j]+H[i][j];
tempH[i][j]=tempH[i][j]+dx[i]*dx[j]/num1;
tempH[i][j]=tempH[i][j]-Hg[i]*gH[j]/num2;
}
}
for(i=0;i{
for(j=0;j{
H[i][j]=tempH[i][j];
}
}
/////////////////////////////
//P
for(i=0;ifor(i=0;i{
for(j=0;j{
p[i]=p[i]-H[i][j]*g1[j];
}
}
for(i=0;i{
g0[i]=g1[i];
x0[i]=x1[i];
}
k=k+1;
}while(g_norm>e);
for(i=0;idelete[]g0;
delete[]g1;
delete[]dg;
delete[]p;
delete[]x0;
delete[]x1;
delete[]dx;
for(i=0;idelete[]H;
for(i=0;idelete[]tempH;
delete[]gH;
delete[]Hg;
returnpf(min_point);
}
/////////////
doublefun(double*x)
{
return100*(x[1]-x[0]*x[0])*(x[1]-x[0]*x[0])+(1-x[0])*(1-x[0]);
}
voidmain()
{
intn=2;
doublemin_point[2]={-5,10};
doublemin_value=DFP(fun,n,min_point);
cout<}
//0.618法线搜索
//
//参数:
指向目标函数的指针,变量个数,出发点,搜索方向
//返回:
最优步长
//
doubleline_search1(
double(*pf)(double*x),
intn,
double*start,
double*direction)
{
inti;
intk;
doublel,a,b,c,u,lamda,t,e;
double*xa=newdouble[n];
double*xb=newdouble[n];
double*xc=newdouble[n];
double*xl=newdouble[n];
double*xu=newdouble[n];
//确定初始搜索区间
l=0.001;
a=0;
k=0;
do
{
k++;
c=a+l;
for(i=0;i{
xc[i]=start[i]+c*direction[i];
xa[i]=start[i]+a*direction[i];
}
l=l/3;
}while(pf(xc)>=pf(xa));//?
?
?
k=0;
do
{
k++;
l=2*l;
b=c+l;
for(i=0;i{
xc[i]=start[i]+c*direction[i];
xb[i]=start[i]+b*direction[i];
}
a=c;
c=b;
}while(pf(xb)<=pf(xc));
a=0;
b=0.1;
//寻优
t=0.618;
e=0.000001;
lamda=b-t*(b-a);
u=a+t*(b-a);
for(i=0;i{
xl[i]=start[i]+lamda*direction[i];
xu[i]=start[i]+u*direction[i];
}
k=0;
do
{
k++;
if(pf(xl){
b=u;
u=lamda;
lamda=b-t*(b-a);
}
else
{
a=lamda;
lamda=u;
u=t*(b-a);
}
}while(b-a>=e);
lamda=(a+b)/2;
delete[]xa;
delete[]xb;
delete[]xc;
delete[]xl;
delete[]xu;
returnlamda;
}