Diff: main.cpp

Revision:

0:904ead7b9c3a

Child:

1:5ec4a7674069

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Dec 22 12:42:04 2021 +0000
@@ -0,0 +1,100 @@
+#include "mbed.h"
+#define ITMAX 100
+#define CGOLD 0.3819660
+#define SHIFT(a,b,c,d) (a)=(b);(b)=(c);(c)=(d);
+#define ZEPS 1.0e-10
+Serial pc(USBTX,USBRX);
+double f(double x);
+double brent(double min,double mid,double max,double tol);
+double SIGN(double x,double y);
+
+double brent(double min,double mid,double max,double tol)
+{
+    int iter;
+    double a,b,d,etemp,fu,fv,fw,fx,p,q,r,tol1,tol2,u,v,w,x,xm,xmin;
+    double e=0.0;
+    a=(min < max ? min : max);
+    b=(min > max ? min : max);    
+    x=w=v=mid;
+    fw=fv=fu=f(x);
+    for(iter=1;iter<=ITMAX;iter++)
+    {
+        xm=0.5*(a+b);
+        tol2=2.0*(tol1=tol*fabs(x)+ZEPS);
+        if(fabs(x-xm)<=(tol2-0.5*(b-a)))
+        {
+            xmin=x;
+            return xmin;
+        }
+        if(fabs(e)>tol1)
+        {
+            r=(x-w)*(fx-fv);
+            q=(x-v)*(fx-fw);
+            p=(x-v)*q-(x-w)*r;
+            q=2.0*(q-r);
+            if(q>0.0)p=-p;
+            q=fabs(q);
+            etemp=e;
+            e=d;
+            if(fabs(p)>=fabs(0.5*q*etemp)||p<=q*(a-x)||p>=q*(b-x))
+            {  d=CGOLD*(e= (x>=xm ? a-x : b-x));}
+            else
+            {
+               d=p/q;
+               u=x+d;
+               if(u-a < tol2 || b-u < tol2)
+               {d=SIGN(tol1,xm-x);}
+            }
+        }
+        else
+        {
+            d=CGOLD*(e= (x>=xm ? a-x : b-x));
+            }    
+        u=(fabs(d) >= tol1 ? x+d : x+SIGN(tol1,d));
+        fu=f(x);
+         if(fu <= fx)
+         {
+            if(u >= x)a=x; else b=x;
+            SHIFT(v,w,x,u);
+            SHIFT(fv,fw,fx,fu);
+          }
+         else{
+          if(u < x){a=u;} 
+          else {b=u;}
+          if(fu <= fw || w==x)
+          {
+              v=w;
+              w=u;
+              fv=fw;
+              fw=fu;
+              }    
+          else if (fu <= fv || v==x || v==w)
+          {
+            v=u;
+            fv=fu;
+          }
+        }
+        
+        }
+    return xmin;
+    }
+//極小値を求めたい関数を定義    
+double f(double x){
+    double x_return;
+    x_return=x*x;
+    return x_return;
+    }   
+double SIGN(double x,double y)
+{
+    double x_return;
+    x_return=abs(x);
+    if(y<0.0)x_return=-x_return;
+    printf("f");
+    return x_return; 
+    }     
+int main() {
+   double x;
+   x= brent(-100.0,10.0,100.0,0.0000000001);
+   printf("%lf\r\n",x);
+   return 0;
+}