CODEWITHSUNDEEP
arraysfor-loop
handroski
handroski

Reputation: 101

Manipulating a loop

I am trying to calculate for successive layers of a planets mass using a volume array and a uniform density. The volume starts from 0 which will give the volume between the center and the 1st shell. So I need to calculate the mass starting from there and then each layer from there. The problem I am getting into is that i need to add the calculated mass before that to get the total mass ( where the + imass[k-1] comes into play. I want to end up with total planet mass at the surface. Could I ignore that addition in the first for-loop since it wont be there?

public class MassGrids { 

    public double imass[];

    // Initial mass with uniform density

    public MassGrids ( int shells , double radius , double mass ){           // constructor for mass grids 


        VolGrid vg = new VolGrid ( shells, radius );                    // calls volume to be used 

        IntlDensity rho = new IntlDensity ( mass, radius );         // calls INITIAL Density

        imass = new double [ shells ] ;                     // Fills mass array with number of elements, shells

        for ( int k = 0 ; k <= shells - 1 ; k++ ){              // For loop will define each element in array

            imass[ k ] = ( vg.vol[k] * rho.irho ( mass, radius ) + imass [ k - 1 ]) ;

            System.out.println(imass[k]);

        }

    }

Upvotes: 0

Views: 50

Answers (2)

Nishant Lakhara
Nishant Lakhara

Reputation: 2445

for ( int k = 0 ; k <= shells - 1 ; k++ ){              // For loop will define each element in array
            if(k>0)
            imass[ k ] = ( vg.vol[k] * rho.irho ( mass, radius ) + imass [ k - 1 ]) ;
            else
            imass[ k ] = vg.vol[k] * rho.irho ( mass, radius );               

            System.out.println(imass[k]);

        }

Yes you can ignore the addition at first loop. Because there is no mass element at -1 index location.

Upvotes: 0

johan
johan

Reputation: 26

why not put the first calculation outside the for loop? like this. 

    imass[ 0 ] = ( vg.vol[0] * rho.irho ( mass, radius )) ;        
        for ( int k = 1 ; k <= shells - 1 ; k++ ){              // For loop will define each element in array

        imass[ k ] = ( vg.vol[k] * rho.irho ( mass, radius ) + imass [ k - 1 ]) ;

        System.out.println(imass[k]);

    }

Upvotes: 1

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