# Multiplying elements of a vector

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Stephen Warren on 28 Jun 2020
Edited: madhan ravi on 28 Jun 2020
I'm creating a function to find areas of shapes. It takes two inputs, the first is a vector and the second is a variable number.
function area = area_calculator(A, num)
switch num
case 1 % Circle
r = norm(A);
A = pi*r^2 % Area
case 2 % Rectangle
A = b*h % Area; I want to multiply vector element 1 by vector element 2
end
So if I give it
>> area_calculator([2,4], 2)
I'm wanting b*h to be 2*4
I'm unsure how to instruct matlab to perform multiplication within the vector
Thank you very much

madhan ravi on 28 Jun 2020
Edited: madhan ravi on 28 Jun 2020
Use prod() to perform multiplication within a vector.
function area = area_calculator(vector, num)
switch num
case 1 % Circle
r = norm(vector);
area = pi*r^2 % Area
case 2 % Rectangle
area = prod(vector);% or you can use vector(1)*vector(2) % Area; I want to multiply vector element 1 by vector element 2
end

per isakson on 28 Jun 2020
Replace
case num == 1
by
case 1

#### 1 Comment

Stephen Warren on 28 Jun 2020
Thanks, that makes it cleaner.
How do I perform multiplication of elements from within one vector