Onsite Interview from MathWork 2015 Fall

I had a onsite interview at MathWork today. Sadly I didn’t make it.

A Indin girl took gave me the interview. The tech interview has 4 parts

algorithm test

Write down any sorting algorithm

C++

There are 4 pages of C++ code and you need to find out the output

1. The first one is about shallow and deep copy

2. The behavior of virtual destructor

    #include <iostream>
    Class A
    {
    public:
        ~A()
        {
            std::cout<<"A"<<std::endl;
        }
    }
    Class B
    {
    public:
        ~B()
        {
            std::cout<<"B"<<std::endl;
        }
    }
   
    void main()
    {
        A* ptr = new B;
        delete ptr;
        return;
    }
   

3. Static class member

4. Behavior of array pointer

    #include <iostream>
    void main()
    {
        int arr[] = {0,1,2,3,4};
        //int* ptr = arr;
        std::cout<<*(arr+1)<<std::endl;
        std::cout<<*(arr++)<<std::endl;
        return;
    }
   

Matlab

She told me to choose another language for test. I thought my Matlab is good until I saw the questions.

Scenario 1

The first scenario is the proccess data.

1. How to optimize the following code

    sensorData = [50, 30, 45, 36, 45];
    scalePara = [2, 6, 8, 32, 10, 32];
    for sensor = 1 : 5
        scaledData(sensor) = sensorData(sensor) / scalePara(sensor);
    end
   

2. How to optimize the code if (data still needed to be divided by the scaledPara, which means that you need to do it row by row). I used a loop over the rows, but there must be better ways to do this.

    sensorData = [50, 30, 45, 36, 45,
            52, 32, 74, 23, 68,
            20, 30, 48, 95, 30];
   

Scenario 2

1. If you are writing a project in Matlab, would you use function or script.
2. If you have a function to do clean up, is it a good idea to name the function “end”?

Scenario 3

1. If you have a 4 sensor with each sensor has 1000 data, how do you visualize the data.

2. How would you differentiate the different data from different sensors.

Scenario 4

1. If you have lines of repeatation to calculate something, what would you do.

2. If you have a complicated calculation in one line and there are many lines like it, how do you optimize without write another function.

Math

It’s really simple the first one is a linear function with porperty

F(A+B) = F(A) + F(B)
F(kA) = kF(A)