Help with structs...

Hi, I have to do an assignment(explained in code) and I keep getting this error:

PHP Code:

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In function 'int main()':
error: conversion from 'Point' to non-scalar type 'MathVector' requested 


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(The little red x is at the last line in main)
Can someone please tell me what I need to change in order to make this program work. Thank you.

Code:

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// This program reads and stores start and end coordinates of two vectors// and then determines if the vectors are orthogonal or not using the
// dot product equation


// including required libraries
#include <iostream>
#include <cmath>


// using namespace
using namespace std;


// struct definitions & declarations
struct Point
{
    double x;
    double y;
    double z;
};


struct MathVector
{
Point start;
Point end;
};


// Function prototypes
Point ReadPoint();
double DistanceBetweenPoints( const Point& pt1, const Point& pt2 );
void Dot_Product ( MathVector sa,  MathVector ea,  MathVector sb, MathVector eb);


// main function
int main()
{
    Point starta = ReadPoint();
    Point enda = ReadPoint();
    Point startb = ReadPoint();
    Point endb = ReadPoint();


    Dot_Product (starta, enda, startb, endb);
}


// function definition
Point ReadPoint()
{
    double x1;
    double y1;
    double z1;


cout << "Enter the coordinates x, y, and z of the point: ";
cin >> x1 >> y1 >> z1;


Point pt1;
    pt1.x=x1;
    pt1.y=y1;
    pt1.z=z1;


return pt1;
}




double DistanceBetweenPoints( const Point& pt1, const Point& pt2 )
{
    double x1= pt1.x;
    double x2= pt2.x;
    double y1= pt1.y;
    double y2= pt2.y;
    double z1= pt1.z;
    double z2= pt2.y;


double distance = sqrt(pow((x1-x2),2)+pow((y1-y2),2)+pow((z1-z2),2));


return distance;
}


void Dot_Product ( MathVector sa,  MathVector ea,  MathVector sb, MathVector eb)
{
    double x_starta = sa.start.x;
    double x_enda = ea.end.x;
    double x_startb = sb.start.x;
    double x_endb = eb.end.x;
    double y_starta = sa.start.y;
    double y_enda = ea.end.y;
    double y_startb = sb.start.y;
    double y_endb = eb.end.y;
    double z_starta = sa.start.z;
    double z_enda = ea.end.z;
    double z_startb = sb.start.z;
    double z_endb = eb.end.z;


    double product = (x_enda-x_starta)*(x_endb-x_startb)+ (y_enda-y_starta)*(y_endb-y_startb)+(z_enda-z_starta)*(z_endb-z_startb);


    if (product == 0)
        cout << "The vectors are orthogonal.";


    else
        cout << "The vectors are not orthogonal.";
    return;
}

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You declared your dot product function to take 4 vectors but then pass in 4 points. That's the syntactical error. From a mathematical point of view I don't understand your code. A mathematical vector is nothing but a point with a different definition. (4/2/17) is a vector. A vector is not defined by two points because that would limit it to exactly one start and one end. A dot product takes two vectors. Not 4.

You know, it probably doesn't matter a lot but, a vector *isn't* a line segment!

What you've tried to build is a line segment, with a start and an end. A mathematical vector has only direction and magnitude, not position, thus the possible ways to represent it is by either a n-sized column holding the "cartesian" coordinates of the origin added with it, or a (n-1)-sized column holding its "polar" coordinates and nth element for lenght.

( Just to keep heads spinning... :p )