C++

Forum

 
cpp_int error for large integer constant with boost multiprecision

dinesh999lama (37)
I need to save a very large integer in a variable, after i found that i can use boost::multiprecision::cpp_int i tried to use this in my program, but i'm not getting the proper value when i run the program. My program to test this method is:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
 
    #include <boost/multiprecision/cpp_int.hpp>
    #include <iostream>
    #include <iomanip>
    #include <vector>
    
    
    void print_factorials()
    {
       using boost::multiprecision::cpp_int;
       cpp_int limit = (cpp_int(1) << 128) - 1;
       std::cout<<limit<<std::endl;
       cpp_int factorial = 100000000000000000000000000u;
       std::cout<<factorial<<std::endl;
    }
    int main() {
       print_factorials();
       return 0;
}
Its output are:

1
2
 
    340282366920938463463374607431768211455
    15908979783594147840

with one warning message:

1
2
 
    warning: integer constant is too large for its type [enabled by default]
        cpp_int factorial = 100000000000000000000000000u;

My real program where i need to use this is like:

1
2
 
    I1=70; I2=70; I3=70; I4=70; I5=456; I6=456; I7=456; I8=456; I9=456; I10=456; I11=456; I12=456;
    cpp_int key = i12+I12*(i11+I11*(i10+I10*(i9+I9*(i8+I8*(i7+I7*(i6+I6*(i5+I5*(i4+I4*(i3+I3*(i2+I2*i1))))))))));

Where i1..i12 are positive integers in from 0 to its corresponding I. eg. i1<=>I1. I am doing this for raw-major order calculation where i have got 13 dimension array and i am calculating the offset value of the given address in that array instead of saving given value in 13 dimension array, cas using 13 dimension array, or map is not practical for me since i also need it to write it in file and read it in another program using boot::serialization.

Last edited on
Peter87 (11175)
You can't have integer literals that are bigger than what any of the built-in integer types can handle. I think you can get it to work by instead passing the value as a string to the cpp_int constructor.

 
 
cpp_int factorial("100000000000000000000000000");
Last edited on
dinesh999lama (37)
Thank u u solved my problem. But the number key i.e 10000... is calculated as integer as cpp_int or int than how should i put it inside the cpp_int factorial as string? I tried this method but its not working:
1
2
3
4
5
6
 
#include <string> 
#include <iostream>
int main() {
std::string s = std::to_string(10000000000000000000000);
std::cout<<s<<std::endl;
}
Last edited on
Chervil (7320)
This is recreating another version of the same error:
 
 
std::string s = std::to_string(10000000000000000000000);

Instead you might do simply 
 
 
std::string s = "10000000000000000000000";
dinesh999lama (37)
But here the string s is calculated as a number so how do i put inside the string s. 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
 
    int I1, I2, I3, I4, I5,I6,I7,I8,I9,I10,I11,I12; int i1,i2,i3,i4,i5,i6,i7,i8,i9,i10,i11,i12;
     I1=70; I2=70; I3=70; I4=70; I5=456; I6=456; I7=456; I8=456; I9=456; I10=456; I11=456; I12=456;
     map<double,int> p0obj, p1obj, p2obj, size_p; int count = 0;
     int d[17];  std::ofstream s("filename");
     boost::archive::text_oarchive oa(s);
     for(int p0=0;p0<a.size() && ros::ok();p0+=5) {
        for(int p1=0;p1<a.size() && ros::ok();p1++) {
           int d1 = sqrt(pow(a.at(p1)-a.at(p0),2)+pow(b.at(p1)-b.at(p0),2)+pow(c.at(p1)-c.at(p0),2))*1000; 
           if(d1==20) { 
             for(int p2=0;p2<a.size() && ros::ok();p2++) { 
                int d2 = sqrt(pow(a.at(p2)-a.at(p0),2)+pow(b.at(p2)-b.at(p0),2)+pow(c.at(p2)-c.at(p0),2))*1000;
                int d1d = sqrt(pow(a.at(p2)-a.at(p1),2)+pow(b.at(p2)-b.at(p1),2)+pow(c.at(p2)-c.at(p1),2))*1000;
                if(d2==20 && d1d==20) {
                  float a1 = a.at(p1)-a.at(p0); float b1 = b.at(p1)-b.at(p0); float c1 = c.at(p1)-c.at(p0);
                  float a2 = a.at(p2)-a.at(p0); float b2 = b.at(p2)-b.at(p0); float c2 = c.at(p2)-c.at(p0);
                  float a3r = b1*c2-b2*c1; float b3r = a2*c1-a1*c2; float c3r = a1*b2-a2*b1;
                  float a3, b3, c3;
                  if(c3r>0) {
                    a3 = a3r/sqrt(a3r*a3r+b3r*b3r+c3r*c3r);
                    b3 = b3r/sqrt(a3r*a3r+b3r*b3r+c3r*c3r);
                    c3 = -c3r/sqrt(a3r*a3r+b3r*b3r+c3r*c3r);
                  }
                  else {
                      a3 = a3r/sqrt(a3r*a3r+b3r*b3r+c3r*c3r);
                      b3 = b3r/sqrt(a3r*a3r+b3r*b3r+c3r*c3r);
                      c3 = c3r/sqrt(a3r*a3r+b3r*b3r+c3r*c3r);
                  }
                  float x3 = (a.at(p0)+a.at(p1)+a.at(p2)/3)+0.02*a3;
                  float y3 = (b.at(p0)+b.at(p1)+b.at(p2)/3)+0.02*b3;
                  float z3 = (c.at(p0)+c.at(p2)+c.at(p2)/3)+0.02*c3;
                  for(int p4=0;p4<a.size() && ros::ok();p4++) {
                     int d0r = sqrt(pow(a.at(p4)-a.at(p0),2)+pow(b.at(p4)-b.at(p0),2)+pow(c.at(p4)-c.at(p0),2))*1000;
                     int d1r = sqrt(pow(a.at(p4)-a.at(p1),2)+pow(b.at(p4)-b.at(p1),2)+pow(c.at(p4)-c.at(p1),2))*1000;
                     int d2r = sqrt(pow(a.at(p4)-a.at(p2),2)+pow(b.at(p4)-b.at(p2),2)+pow(c.at(p4)-c.at(p2),2))*1000;
                     int d4r = sqrt(pow(x3-a.at(p1),2)+pow(y3-b.at(p1),2)+pow(z3-c.at(p1),2)); 
                     if(d0r>0 && d1r>0 && d2r>0 && d4r>0 && d0r<=70) {
                       i1=d0r; i2=d1r; i3=d2r; i4=d4r; 
                       i5=ac.at(p0); i6=bc.at(p0);
                       i7=ac.at(p1); i8=bc.at(p1); 
                       i9=ac.at(p2); i10=bc.at(p2); 
                       i11=ac.at(p4); i12=bc.at(p4);
                       double key = i12+I12*(i11+I11*(i10+I10*(i9+I9*(i8+I8*(i7+I7*(i6+I6*(i5+I5*(i4+I4*(i3+I3*(i2+I2*i1))))))))));
                       p0obj[key] = p0; p1obj[key] = p1; p2obj[key] = p2; size_p[key]++;
                       oa << p0obj; oa << p1obj; oa << p2obj; oa << size_p;
                       cout<<++count<<"\t"<<key<<"\t"<<p0obj[key]<<"\t"<<p1obj[key]<<"\t"<<p2obj[key]<<"\t"<<size_p[key]<<endl;
                     }
                   }
                 }
               }
            }
         }
      }
                                      
     cout<<"finish one loop"<<endl;

This is how i am calculating the key value which has to be saved as either sting or int for map, so i can use these pattern of given object in another program for object detection purpose.
Last edited on
Chervil (7320)
But here the string s is calculated as a number so how do i put inside the string s.

Which number in that block of code is the one you are interested in?
If it is an ordinary int, then std::to_string will work. If it is a string, then keep it as a string.
dinesh999lama (37)
In above code, it is double key which i was trying to convert into string. But since double is not appropriate for this task, i went to cpp_int now that is also not working properly. Here key is the row major order of the 13 dimension array calculated by above formula which i found in wikkipedia, the forumula was given in alzebric expression so i expanded it for my use. I am calculating this raw major order so that i can use this as key value for map and than save it in a file than read the same in another program by using serialization. Since the file is very large i am doing this.
kbw (9488)
If you want to work with large floating point numbers, then yes, MPFR is the way to go.

If you want to work with large integers, you need a BigNum library. There are many implementations on this forum (somewhere) and of course, there's The Internet.
Topic archived. No new replies allowed.