Element-By-Element Operations using Matlab

I wonder how to calculate the following sum using Element-By-Element Operations Matlab:

    ∑_(i=1)^4(u_i.[min(0,A_i.x-b_i )]^2)

i=1:4

u_i is a scalar

A_i is a (1,4) vector

b_i is a scalar

and

x is a (4,1) vector

Answer 1

[Andrei Bobrov]

u*min(0,A*x-b).^2;

[imed NASRI]

It doesn't work.

u is a (1,4) vector

A is a (4,4) matrix

x is a (4,1) vector and

b is a (4,1) vector

[imed NASRI]

I want to calculate automatically this sum:

u(1)*[min(0,A(1,:)*x-b(1))]^2+u(2)*[min(0,A(2,:)*x-b(2))]^2+u(3)*[min(0,A(3,:)*x-b(3))]^2+u(4)*[min(0,A(4,:)*x-b(4))]^2

[Andrei Bobrov]

I corrected

Answer 2

[Biswajit M]

hope this helps:

u(1)*(min(0,min(A(1,:)))*x-b(1)) .^2+u(2)*(min(0,min(A(2,:)))*x-b(2)) .^2+u(3)*(min(0,min(A(3,:)))*x-b(3)) .^2+u(4)*(min(0,min(A(4,:)))*x-b(4)) .^2

I tried it this way :

clear all; clc

u=[1,2,3,4]; A=[1,2,3,4;5,6,7,8;1,2,3,4;5,6,7,8]; x=[5;6;7;8]; b=[4;5;6;7]; min(0,min(A(1,:)))

u(1)*(min(0,min(A(1,:)))*x-b(1)) .^2+u(2)*(min(0,min(A(2,:)))*x-b(2)) .^2+u(3)*(min(0,min(A(3,:)))*x-b(3)) .^2+u(4)*(min(0,min(A(4,:)))*x-b(4)) .^2

The output comes like:

ans =

   370
   370
   370
   370

[imed NASRI]

My vectors have sometimes a size (1000). In this case your équation becomes so hard to write. I Wonder if i can use a loop to calculate automatically this sum??!!!