I have a segmentation fault 11 in this piece of code (edit:no longer shown).
Having been told to get a debugger and to sort my arrays out I have edited the code to fix the arrays to go from 0. I also installed valgrind and ran it but it is limited when working on OSX. I have run gbd and the issue is described below.
If this just looks horrendously ominous, or the code is needed to make any kind of headway, let me know and I can edit the question to the format the forum expects.
Running gdb on my code I get:
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x00007fff5e4c27c8
0x0000000100001048 in main () at TammesA3.cc:23
23 mpf_set_default_prec(1024);
The code is as follows and the issue is caused before my loops later on even start!
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <time.h>
#include <stdlib.h>
#include <sstream>
#include <gmpxx.h>
using namespace std;
#define PI 3.14159265358979323846
mpf_t E[100000];
int main()
{
int a,b,c,d,f,i,j,k,m,n,s,Success,Fails;
double p,theta,phi,Time,Averagetime,Distance,Length,DotProdForce,
Forcemagnitude,ForceMagnitude[200],Force[200][3],Epsilon[3],
x[200][3],new_x[200][3],y[200][3],A[200],alpha[200][200],degree,bestalpha[500];
unsigned long int t;
mpf_set_default_prec(1024);
mpf_t Energy,energy,Power,D,En[500],Ep,e;
mpf_init(Power);
mpf_init(D);
mpf_init(Ep);
mpf_init(e);
mpf_init(Energy);
mpf_init(energy);
for(i=0;i<100000;i++){
mpf_init(E[i]);
}
for(i=0;i<500;i++){
mpf_init(En[i]);
}
mpf_set_d(e,0.00000000000000000000000000000000000000000000000000000000001);
clock_t t1,t2;
t1=clock();
t=1000;
while(t<1001){
n=20;
while(n<21){
cout << "N=" << n << "\n";
b=1;
Time=0.0;
while(b<2){
clock_t t3,t4;
t3=clock();
if(n>200){
cout << n << " is too many points for me :-( \n";
exit(0);
}
srand((unsigned)time(0));
for (i=0;i<n;i++){
x[i][0]=((rand()*1.0)/(1.0*RAND_MAX)-0.5)*2.0;
x[i][1]=((rand()*1.0)/(1.0*RAND_MAX)-0.5)*2.0;
x[i][2]=((rand()*1.0)/(1.0*RAND_MAX)-0.5)*2.0;
Length=sqrt(pow(x[i][0],2)+pow(x[i][1],2)+pow(x[i][2],2));
for (k=0;k<3;k++){
x[i][k]=x[i][k]/Length;
}
}
for(i=0;i<n;i++){
for(j=0;j<3;j++){
cout << "x[" << i << "][" << j << "]=" << x[i][j] << "\n";
}
}
/* Points distributed randomly and normalised so they sit on unit sphere */
mpf_set(Energy,0);
for(i=0;i<n;i++){
for(j=i+1;j<n;j++){
Distance=sqrt(pow(x[i][0]-x[j][0],2)+pow(x[i][1]-x[j][1],2)
+pow(x[i][2]-x[j][2],2));
mpf_set_d(D,Distance);
mpf_pow_ui(Power,D,t);
mpf_ui_div(Power,1.0,Power);
mpf_add(Energy,Energy,Power);
}
} etc.
after this, my code goes on into a loop, but the code as said in comments in really long so shan't put it in again unless requested.
The remaining problem(1) is (on three lines)
mpf_set(Energy,0);
Its prototype is
void mpf_set (mpf_t ROP, mpf_t OP)
and an mpf_t is an array,
typedef __mpf_struct mpf_t[1];
so you pass a null pointer for the value to read. Dereferencing a null pointer is another typical cause of segmentation faults (besides accessing beyond array bounds).
You meant to use mpf_set_d, mpf_set_ui or mpf_set_si there (which one you use doesn't matter).
(1) I have copied the code from revision 2 and moved the two big arrays E and alpha to file scope to relieve the stack of that burden, after that and fixing three mpf_set(variable,0) on lines 94, 147 and 271, it ran to completion.
That doesn't necessarily mean the code is correct, at the end of the output I read
Successes=0 Failures=1
Success Rate=0.00000
which hints at a possible problem in the code logic, but I don't know what output to expect.