## Spacemacs

I will update this post soon as my day job leaves little time for fun aspects like this.

Spacemacs’ new Haskell layer is what I like now eventhough the Haskell editor setup is not easy for the novice.

After installing Spacemacs these are the basic steps I followed.

;; —————————————————————-
;; Example of useful layers you may want to use right away.
;; Uncomment some layer names and press (Vim style) or
;; (Emacs style) to install them.
;; —————————————————————-
;; auto-completion
;; better-defaults
emacs-lisp
;; git
;; markdown
;; org
;; (shell :variables
;; shell-default-height 30
;; shell-default-position ‘bottom)
;; spell-checking
;; syntax-checking
;; version-control

(defun dotspacemacs/user-init ()
“Initialization function for user code.
It is called immediately after dotspacemacs/init’, before layer configuration
executes.
This function is mostly useful for variables that need to be set
before packages are loaded. If you are unsure, you should try in setting them in
dotspacemacs/user-config’ first.”
)

C:/Users/476458/AppData/Roaming/local/bin/ contains other tools installed by Stack.

Stack is a cross-platform program for developing Haskell projects. It is aimed at Haskellers both new and experienced.

Suggested by spacemacs Reddit group

(defun dotspacemacs/user-config ()
“Configuration function for user code.
This function is called at the very end of Spacemacs initialization after
layers configuration.
This is the place where most of your configurations should be done. Unless it is
explicitly specified that a variable should be set before a package is loaded,
you should place your code here.”
)
)

This helps me compile and execute the Haskell program by using the keystrokes

SPC m c x

## Getting introduced to Matlab

There was a time when I thought Matlab is a tool used by engineers. Is it even possible for a student of humanities to get access to such tools ? It is and there are academic licenses.

##### Matrix

matrix = zeros(10,10);

matrix(1,2) = 3
matrix(2,2) = 30
matrix(1,3) = 2
matrix(4,3) = 14
matrix(5,2) = 199
matrix(6,2) = 733


$\begin{bmatrix} 0 & 3 & 2 & 0 & 0\\ 0 & 30 & 0 & 0 & 0\\ 0 & 0 & 0 & 0 & 0\\ 0 & 0 & 14 & 0 & 0\\ 0 & 199 & 0 & 0 & 0\\ 0 & 733 & 0 & 0 & 0\\ \end{bmatrix}$

##### Maximum value from a matrix
[max_value, node] = max(matrix(:));

fprintf ('Maximum value is %d and node is %d\n', max_value, node);



node seems to be a reference to the element which is used below to get the row and column using ind2sub.


[i, j] = ind2sub(size(matrix), node);

fprintf ('Row is %d and column is %d\n', i, j);



sub2ind gives the linear indice of the element when we have the row and column of the element.


linearindice = sub2ind(size(matrix), 1, 2);

fprintf ('Linear Indice is %d \n', linearindice);


##### Sort

I get the sorted matrix and also the matrix of indices of the sorted elements. Very useful.


[values, indices] = sort( matrix );

##### Sorted values

$\begin{bmatrix} 0 & 0 & 0 & 0 & 0\\ 0 & 0 & 0 & 0 & 0\\ 0 & 3 & 0 & 0 & 0\\ 0 & 30 & 0 & 0 & 0\\ 0 & 199 & 2 & 0 & 0\\ 0 & 733 & 14 & 0 & 0\\ \end{bmatrix}$

##### Indices of sorted values

$\begin{bmatrix} 1 & 3 & 2 & 1 & 1\\ 2 & 4 & 3 & 2 & 2\\ 3 & 1 & 5 & 3 & 3\\ 4 & 2 & 6 & 4 & 4\\ 5 & 5 & 1 & 5 & 5\\ 6 & 6 & 4 & 6 & 6\\ \end{bmatrix}$