From bf2b9d08063578f25fe1cc90b31e7545f0bf524d Mon Sep 17 00:00:00 2001
From: ehudbehar <ehud.behar@protonmail.com>
Date: Mon, 27 Sep 2021 22:16:28 +0300
Subject: [PATCH] Add 8 Matlab questions (#2270)

Improved formatting in q54 and add 8 question in Matlab-quiz.md

Co-authored-by: Zhenja <evg.bazhanov@yahoo.com>
---
 matlab/matlab-quiz.md | 74 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 70 insertions(+), 4 deletions(-)

diff --git a/matlab/matlab-quiz.md b/matlab/matlab-quiz.md
index 33a3a76b3f..eb20f3f53d 100755
--- a/matlab/matlab-quiz.md
+++ b/matlab/matlab-quiz.md
@@ -819,12 +819,14 @@ a = a^2;
 
 #### Q54. Which choice is the correct syntax for declaring a function that returns the input value as the output?
 
+- [ ]
+
 ```
 function mystery_func(a) :
     return a
 ```
 
-- [ ]
+- [x]
 
 ```
 function b = mystery_func(a)
@@ -832,7 +834,7 @@ function b = mystery_func(a)
 end
 ```
 
-- [x]
+- [ ]
 
 ```
 def b = mystery_func(a)
@@ -849,8 +851,6 @@ function mystery_func(a)
 end
 ```
 
-- [ ]
-
 [Reference](https://mathworks.com/help/matlab/ref/function.html)
 
 #### Q55. What is the state of a at the end of this code?
@@ -902,3 +902,69 @@ a =
 - [x] `h_a = gca; set(h_a,'Color', [0 0 0]);`
 - [ ] `h_a = axes; set(h_a,'Color', [0 0 0]);`
 - [ ] `h_f = gcf; set(h_a,'Color', [0 0 0]);`
+
+#### Q57. Which statement will return all the odd numbers from 1 to 9?
+
+- [ ] `2*[1:5]+1`
+- [x] `1:2:9`
+- [ ] `isodd(1:9)`
+- [ ] `1:odd:9`
+
+#### Q58. In MATLAB, the `imfilter` command performs a convolution operation between an image and a matrix. Suppose you have an image loaded in MATLAB into the variable `img` and you apply the following code. The original image appears slightly blurred because the convolution smoothed out the image (removed noise). Why do you think this happened? 
+
+```
+h = ones(5,5)/25;
+imshow(imfilter(img,h)); 
+```
+- [ ] `h` is a Gaussian filter that adds to 1. Its intended effect is to highlight image edges.
+- [x] `h` is an averaging filter uniformly distributed that adds to 1. Its intended effect is to smooth out images (remove noise).
+- [ ] `h` is a Laplacian filter that adds up to 0. Its intended effect is to smooth out images (remove noise).
+- [ ] `imfilter` is a function that always blurs the images.
+
+#### Q59. What is the size of `b`?
+
+```
+a = [1 2 3];
+b = repmat(a,2,3);
+```
+
+- [ ] 1x3
+- [ ] 3x2
+- [ ] 2x3
+- [x] 2x9
+
+#### Q60. Which statement reverses vector `a`?
+
+```
+a = [ 1 2 3 4];
+```
+
+- [ ] reverse(a)
+- [x] a(end:- 1:1)
+- [ ] rev(a)
+- [ ] a(::-1)
+
+#### Q61. Which command will create a column vector with the values 7, 8, and 9?
+
+- [ ] `c = [7,8,9]`
+- [ ] `c = [7: 8: 9]`
+- [x] `c = [7; 8; 9]`
+- [ ] `c = [7 8 9]`
+
+#### Q62. What do you call in the **command** window to see all the variables in the workspace and their classes?
+- [ ] `who`
+- [ ] `vars`
+- [x] `whos`
+- [ ] `who all`
+
+#### Q63. You wrote a new function named `snap` in an m-file and when you call it, you're not getting the output you expect. You previously wrote a different function named `snap`, which you think might also be on the search path. Which command can you use to see if the old `snap` function is being called? 
+- [x] which
+- [ ] who
+- [ ] lookfor
+- [ ] what 
+
+#### Q64. What is a reason to save a MAT-file using the `-v7.3` flag?
+- [ ] to ensure backward compatibility
+- [ ] to avoid HDF5 overhead in MAT-file
+- [x] to include a variable greater that 2GB
+- [ ] to use compression by default