Why won't this Calculation Work?

[Beth Hill]

Hi,
I'm fairly new to programming, and this is my first piece of code beyond drawing pretty patterns in dxf files!
I'm having trouble with line 132 (and probably 134 too). Basically where it calculates F[n][m] the calculation is not executing correctly. e.g. F[1][1]=C[1][1]*K[1], as C[1][1]=0.000169 and K[1]=0.0121 I expect to get F[1][1] in the region of 2e-6 but instead Xcode outputs the result as 1.176e-313!
Can anybody see the problem?
Thanks,
Beth

//  Created by Elizabeth Hill on 29/02/2012.
//  Copyright (c) 2012 Elizabeth Hill. All rights reserved.
#include <iostream>
#include <cmath>
#include <stdlib.h>
#include <fstream>
#include <string>
#define Q 0.0027
#define t 0.00025
#define T 60
#define lmax 0.02
#define g 9.81
using namespace std;
int Wave(double TipPen)
{
    double NewTipPen;

    // SOIL PROFILE

    int d=2;
    double Xud[d];
    double Rsud[d];
    double Rpud[d];

    Xud[1]=0;     // Depth
    Rsud[1]=120000;    // Skin Friction
    Rpud[1]=300000;    // End Bearing
    Xud[2]=3;     // Depth
    Rsud[2]=120000;    // Skin Friction
    Rpud[2]=300000;    // End Bearing

    // DAMPENING

    double J1;  // Toe
    double J2;  // Skin
    J2=0.15;
    J1=0.05;

    // DEFINE PILE SECTIONS

    int m; // Unit
    int p; // Total number of units in Analysis

    p=7;

    double L[p];
    double A[p];
    double P[p];
    double I[p];
    double E[p];
    double Rho[p];
    double W[p];
    double K[p];

    for (m=3; m<=p; m++) {
        L[m]=0.02;
        A[m]=0.01;
        P[m]=0.4;
        I[m]=0.000008333;
        E[m]=200000000000;
        Rho[m]=7750;
        W[m]=Rho[m]*A[m]*L[m]*g;
        K[m]=E[m]*A[m]/L[m];
    }

    // HAMMER PROPERTIES

    double HammerMass;
    double h;
    double eff;
    double eta;

    h=2;
    HammerMass=17.5;
    W[1]=HammerMass*g;
    eff=0.9;
    eta=eff/100;

    L[1]=0.1;
    A[1]=0.01;
    I[1]=0.000008333;
    E[1]=200000000000;

    // CAPBLOCK PROPERTIES

    double CapblockMass; 
    CapblockMass=0.2;

    W[2]=CapblockMass*g;
    L[2]=0.1;
    A[2]=0.01;
    I[2]=0.000008333;
    E[2]=13000000000;
    K[2]=(L[2]/(E[2]*A[2]))+(L[3]/(E[3]*A[3])); // Kirchhoff's law

    // COEFFICIENTS OF RESTITUTION

    double e1;
    double e2;

    e1=0.5;
    e2=0.5;

    int n;
    double X[T][p];
    double D[T][p];
    double Dsoil[T][p];
    double Ksoil[T][p];
    double C[T][p];
    double F[T][p];
    double Ru[T][p];
    double R[T][p];
    double V[T][p];

    // Accelerate the ram

    V[0][1]=eta*sqrt(2*h*g);

    for (n=1; n<=T; n++) {

        for (m=1; m<=p; m++) {

            // DEFLECTIONS - STEP I

            D[n][m]=D[n-1][m]+(V[n-1][m]*12*t);

            // Define Depth Below Mudline

            X[n][m]=D[n][m]+TipPen; 

            // Define ULTIMATE Tip Soil Resistance

            if (m==p) {

                    if (X[n][m]<Xud[2] and X[n][m]>=Xud[1]) {  

                        Ru[n][m]=((((Rpud[2]-Rpud[1])/(Xud[2]-Xud[1]))*(X[n][m]+Xud[1]))+Rpud[1])*A[m];   

                    }

            } else {

                // Define ULTIMATE Skin Resistance

                    if (X[n][m]<Xud[2] and X[n][m]>=Xud[1]) {

                        Ru[n][m]=((((Rsud[2]-Rsud[1])/(Xud[2]-Xud[1]))*(X[n][m]+Xud[1]))+Rsud[1])*L[m]*P[m];   

                    }
                }
            }

            // DEFINE SOIL DEFLECTIONS - STEP II

            if (D[n][m]>Q) {

                if (D[n][m]>D[n-1][m]) {

                    Dsoil[n][m]=D[n][m]-Q; 

                } else {

                    Dsoil[n][m]=Dsoil[n-1][m];
                    NewTipPen=Dsoil[n][m];
                    return NewTipPen;

                }

            } else {

                Dsoil[n][m]=0;   

            }

        // SOIL DEFLECTIONS - STEP III

        R[n][p]=(D[n][p]-Dsoil[n][p])*Ksoil[n][p]*(1+(J1*V[n-1][p]));

        // COMPRESSIONS - STEP IV

        for (m=1; m<p; m++) {

            C[n][m]=D[n][m]-D[n][m+1];   

        }

        // FORCE IN RAM - STEP V    

        F[n][1]=C[n][1]*K[1]; // Calculation Not Executing Properly

        // FORCE IN CAPBLOCK - STEP VI

        F[n][2]=C[n][2]*K[2];

        for (m=3; m<=p; m++) {

            // FORCES IN PILE - STEP VII

            F[n][m]=C[n][m]*K[m];

            // SKIN RESISTANCE ON PILE - STEP VIII

            R[n][m]=(D[n][m]-Dsoil[n][m])*Ksoil[n][m]*(1+(J2*V[n-1][m]));   

        }

        // VELOCITIES - STEP IX

        for (m=1; m<=p; m++) {

            V[n][m]=V[n-1][m]+((F[n][m-1]-F[n][m]-R[n][m])*(t*g/W[m]));       

        }
    }

    // Proof F[1][1] Calc isn't executing properly

    cout << "F[1][1]=" << F[1][1] << "\n";
    cout << "C[1][1]=" << C[1][1] << "\n";
    cout << "K[1]=" << K[1] << "\n";
    cout << "C[1][1]*K[1]=" << C[1][1]*K[1] << "\n\n";

    ofstream WaveCheck("/Users/Folder/Wave Equation/WaveCheck.txt");
    WaveCheck << "Iteration\t" << "Time\t";

    for (m=1; m<=p; m++) {

        WaveCheck << "Displacement[" << m << "]\t" << "Velocity[" << m << "]\t";   

    }

    WaveCheck << "Force in Ram\t" << "Force in Capblock\n" << "(-)\t" << "(s)\t";

    for (m=1; m<=p; m++) {

        WaveCheck << "(m)\t" << "(m/s)\t";   

    }

    WaveCheck << "N\t" << "N\n";

    for (n=1; n<=T; n++) {

        WaveCheck << n << "\t";
        WaveCheck << n*t << "\t";

        for (m=1; m<=p; m++) {

            WaveCheck << D[n][m] << "\t";
            WaveCheck << V[n-1][m] << "\t";

        }

        WaveCheck << F[n][1] << "\t";
        WaveCheck << F[n][2] << "\n";   

    }

    WaveCheck.close();

    return 0;
}

int main(int argc, const char * argv[])
{
    int a;        // Depth Iteration
    int b;        // Total Number of Depths
    double d;     // Size of Depth iterations

    d=0.002;
    b=2;

    double Pen[b];       // Pen Caused by one blow
    double z[b];         // Depth Below Mudline
    double Bl_Ct[b];     // Blows per m

    ofstream Results("/Users/Folder/Results.txt");

    Results << "Depth" << "\t" << "Bl_Ct" << "\n";
    Results << "(meters)" << "\t" << "(-)" << "\n";

    // Blow vs Deformation Table

    for (a=1; a<=b; a++) {

        // Depth for each blow

        z[a]=d*a;
        Pen[a]=Wave(z[a]);

        // Blows per Meter
        Bl_Ct[a]=1/Pen[a];
        Results << z[a] << "\t" << Bl_Ct[a] << "\n";
        cout << Pen[a] << "\t";
        cout << Bl_Ct[a] << "\n";
    }

    Results.close();

    return 0;
}

[Gaminic]

I'm guessing you're referring to lines 189 & 193.

The step before it (181->185) is changing C. Are you sure you're still using the correct values to check your calculation?

It might be a good idea to simply print all numbers involved right before/after the calculation.

[Moschops]

You should be examining the values involved at the point of calculation. Looking at them much later only tells you what they are much later.

Examine the value of K[1] at line 189.

[roberts]

I ran this on VC++ and K[1] is -9.2559631349317831e+061 and K[2] is 7.7923076923076920e-010.

It looks like K[1] never gets initialized.

[Beth Hill]

Thanks I have it now, it was the K[1].