How do use a vector as input to a function?

Hello

I got the following assignment as homwork:

Two rectangular boxes are defined by the coordinates of their lower left and upper right corners

The area of the two boxes are given by A

A1 = (x2 − x1)(y2 − y1), and A2 = (x4 − x3)(y4 − y3).

The area of the intersection between the two boxes is given by

Ao = max (0, min(x2, x4) − max(x1, x3) ) · max (0, min(y2, y4) − max(y1, y3))

Create a function named "boxArea" that takes as input the coordinates defining the two boxes as a vector [x1, x2, x3, x4, y1, y2, y3, y4] as well as a string area that specifies what to compute . The function must return the computed area.

For this i have tried to creat the function:

function A = boxArea(   [x1,x2,x3,x4,y1,y2,y3,y4],area)
switch area 
    case 'Box1'
        A =(x2-x1)*(y2-y1);
    case 'Box2'
        A =(x4-x3)*(y4-y3);
    case 'Intersection'
        A = max(0,min(x2,x4)-max(x1,x3))*max(0,min(y2,y4)-max(y1,y3));
    case'Union'
        A = 'Box1'+'Box2'-'Intersection';
end

But Matlab just returns the errror:

Error: File: boxArea.m Line: 1 Column: 22

Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check

for mismatched delimiters.

How do i fix this? :)

[KSSV]

You have defined the array [x1,x2,x3,x4,y1,y2,y3,y4]..but MATLAB will nt take it as x1, x2, etc..you need to define them inside the function. Check the given answer.

Answer 1

[KSSV]

function A = boxArea(A,area)
x1 = A(1) ; 
x2 = A(2) ; 
x3 = A(3) ; 
x4 = A(4) ; 
y1 = A(5) ; 
y2 = A(6) ; 
y3 = A(7) ; 
y4 = A(8) ; 

switch area 
    case 'Box1'
        A =(x2-x1)*(y2-y1);
    case 'Box2'
        A =(x4-x3)*(y4-y3);
    case 'Intersection'
        A = max(0,min(x2,x4)-max(x1,x3))*max(0,min(y2,y4)-max(y1,y3));
    case'Union'
        A = 'Box1'+'Box2'-'Intersection';
end

[SL: Removed an extra end after the definition of y4. With that end in place, the switch was outside the boxArea function and would cause an error.]