﻿ compute U(x)-L(x), etc.
```/*CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
C                                                                             C
C  COMPUTE SUM OF EULER'S PHI FUNCTION                                        C
C  12/23/14 (DKC)							      C
C                                                                             C
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC*/
#include <stdio.h>
#include <math.h>
unsigned int euclid(unsigned int d, unsigned int e);
//
unsigned int order=50000;
unsigned int out=2;   // losum, hisum, hisum-losum, sqrt((hisum-losum)), sqrt(A(x))
unsigned int flag=0;  // for out=4, sqrt(A(x)), A(x)/sqrt(x(x+1)(2x+1)/6),
// or g(x)/sqrt(x(x+1)(2x+1)/6)
unsigned int flag4=0; // scale for out=4 (zero, plus, or minus)
unsigned int sflag=1; // square root flag (for out=4, normally set to 0)
unsigned int flag2=1; // for out=2, if set compute 1.5x/log(x)-(hisum-losum)
//
void main() {
unsigned int g,h,j,k,l,r;
unsigned int sum,losum,hisum,count;
double misum,esum,edelt;
FILE *Outfp;
Outfp = fopen("out1r1.dat","w");
losum=0;
hisum=1;   // changed from 0 on 08/19/14
misum=1.0;
count=0;
for (g=2; g<=order; g++) {
if (out==4) {
k=g/6;
r=g-k*6;
if (k==0) {
if (r==1)
esum=1.0;
if (r==2)
esum=2.0;
if (r==3)
esum=4.0;
if (r==4)
esum=6.0;
if (r==5)
esum=11.0;
}
else {
esum=12.0*k+23.0*((double)k*(k-1))/2;
edelt=0.0;
if (r==1)
edelt=7.0+6.0*(k-1);
if (r==2)
edelt=11.0+9.0*(k-1);
if (r==3)
edelt=17.0+13.0*(k-1);
if (r==4)
edelt=22.0+16.0*(k-1);
if (r==5)
edelt=33.0+22.0*(k-1);
esum=esum+edelt;
}
}
sum=1;
for (j=2; j<g; j++) {
k=euclid(g,j);
if (k==1)
sum=sum+1;
}
misum=misum+(double)sum;
l=sum/4;
h=l;
if (sum!=l*4)
h=h+1;
else
count=count+1;
losum=losum+l;
hisum=hisum+h;
printf(" %d %d %d %d %e %d \n",g,sum,losum,hisum,misum,(int)(hisum-losum));
if (out==0)
fprintf(Outfp," %d\n",losum);
else {
if (out==1)
fprintf(Outfp," %d\n",hisum);
else {
if (out==2) {
if (flag2==0)
fprintf(Outfp," %d\n",hisum-losum);
else
fprintf(Outfp," %e\n",1.5*(double)g/log((double)g)-(hisum-losum));
}
else {
if (out==3)
fprintf(Outfp," %e\n",sqrt((double)(hisum-losum)));
else {
if (flag==0) {
if (flag4==0) {
if (sflag!=0)
fprintf(Outfp," %e\n",sqrt(misum));
else
fprintf(Outfp," %e\n",misum);
}
if (flag4==1)
fprintf(Outfp," %e\n",0.5513*(double)g+0.2767+0.5);
if (flag4==2)
fprintf(Outfp," %e\n",0.5513*(double)g+0.2767-0.5);
}
else {
if (flag==1)
fprintf(Outfp," %e\n",misum/sqrt((double)g*(double)(g+1)*(double)(2*g+1)/6.0));
else
fprintf(Outfp," %e\n",esum/sqrt((double)g*(double)(g+1)*(double)(2*g+1)/6.0));
}
}
}
}
}
}
printf("count=%d, ratio=%e \n",count,(double)count/(double)order);
fclose(Outfp);
return;
}
```