restruct 1

2 semestr/OldHome/PL/Lessons/Gnuplot/v.c

@@ -0,0 +1,51 @@
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define E 1.0E-5
+#define A1 -2.0
+#define B1 -1.5
+#define A2 -1.0
+#define B2  0.0
+
+char *sf1 = "[-3:1] sin(2*x)-exp(x)\"";
+char *sf2 = "[-3:1] sin(2*x)+exp(x)\"";
+char *gpl = "gnuplot -p -e \"plot ";
+
+#define DBG    
+//gcc filename.c -l m -o filename
+double f1(double x) {
+     return sin(2*x)-exp(x);
+}
+double f2(double x) {
+     return sin(2*x)+exp(x);
+}
+
+double dih(double f(), double a, double b);
+
+int main(){
+    char cmd[128] = "\0";
+    strcat(cmd,gpl);
+    strcat(cmd,sf1);
+    printf("%s\n", cmd);
+    system(cmd);
+    printf("X1 = %.10F\n",dih(f1,A1,B1));
+    printf("X2 = %F\n",dih(f2,A2,B2));
+    return 0;
+}
+
+double dih(double f(), double a, double b){
+    double c;	
+    while( fabs(b-a) > E ) {
+       c = (a+b)/2;
+#ifdef DBG       
+       printf ("%F \n", c );
+#endif
+       if(f(a)*f(c) < 0 )
+           b = c;
+       else
+           a = c;
+    }
+    return c;
+}