×/¨1<⊂|⍳

×/¨1<⊂|⍳  Right argument: h w

       ⍳  Generate all index pairs (1-based) of a h×w array.
     ⊂    Enclose (h w), so it depth matches the one of the index array.
      |   For each pair (i j) compute the remainders of the division by (h w).
   1<     Compare all remainders with 1.
×/¨       Reduce each pair of Booleans by multiplication.

2$l3XyZ+3=

% Grab two input parameters implicitly
2$l     % Create a matrix of ones that has the dimensions specified as inputs
3       % Number literal 3
Xy      % Create a 3x3 identity matrix
Z+      % Perform 2D convolution (preserving size)
3=      % Create a logical matrix where values == 3 are 1 and 0 otherwise (boundary)
        % Implicitly display output.

@(x)conv2(ones(x),eye(3),'s')>2

@(x)imagesc(conv2(ones(x),eye(3),'s')>8)
ans([6,9])

2$lO6Lt4$(

2$l    % Implicit inputs M, N. Generate M×N array of ones
O      % Push number 0
6Lt    % Push [2 -1] twice, corresponding to index "2:end-1"
4$(    % Fill the center of the array with value 0. Implicit display

2$Ol6Lt4$(1YG

>> matl 2$Ol6Lt4$(1YG
> 5
> 7

p%€,>1P€G

p%€,>1P€sG  Main link. Arguments: h (height), w (width)

p           Cartesian product; return all pairs in [1, ..., h] × [1, ..., w].
   ,        Yield the pair [h, w].
 %€         For each pair [i, j] in the product, compute [i % h, j % w].
    >1      Compare all resulting moduli with 1.
      P€    Compute the product of each pair of Booleans.
        s   Split the resulting flat list into rows of length w.
         G  Display the results in a 2D grid.

julia> f(n,m)=[n>i>1<j<m for i=1:n,j=1:m]
f (generic function with 1 method)

julia> f(4,4)
4x4 Array{Bool,2}:
 false  false  false  false
 false   true   true  false
 false   true   true  false
 false  false  false  false

julia> f(1,1)
1x1 Array{Bool,2}:
 false

julia> f(2,5)
2x5 Array{Bool,2}:
 false  false  false  false  false
 false  false  false  false  false

l~S*a*{3a.f|W%z}4*N*

l~       e# Read and evaluate input, dumping h and w on the stack.
S*       e# Create a string of w spaces.
a*       e# Create an array of h copies of that string.
{        e# Repeat this block 4 times...
  3a.f|  e#   For each character in the first row, take its bitwise OR with 3, turning
         e#   spaces into # and leaving # unchanged.
  W%z    e#   Reverse and transpose the grid, rotating it by 90 degrees.
}4*
N*       e# Join the lines of the result with linefeeds.

jQ]Uajt%!RQt%!|

- Q = eval_input()
j               - j = eval_input()
jQ]             - [Q,j]
   U            - create a 3d array sized Q by j with coords
    a           - for each coord (2d for)
     jt%!       -   not (coord_1 % j-1)
              | -  ^ or V
          Qt%!  -   not (coord_2 % Q-1)

jQ]Uajt%RQt%&

(n,m)=>Array(n).fill(' '.repeat(m).replace(/^ | $/g,0)).join`
`.replace(/^.+|.+$/g,'0'.repeat(m))

d+
$*
S_`1(?=.* (1+))|.
T`1`#`^.+|.+$|.?¶.

d+
$*

S_`1(?=.* (1+))|.

T`1`#`^.+|.+$|.?¶.

;'#*;))¬' *'#;)@+(+nXX(

;'#*;))¬' *'#;)@+(+nXX(
                         (implicit) push all input to stack
;'#*                     push a string containing X #s
    ;))                  dupe, and push both to bottom of stack
       ¬' *              push a string containing (X-2) spaces
           '#;)@+(+      add a # to the front and the back of the string
                   nXX   make (Y-2) copies
                      (  bring one of the "#"*X strings back to the top
                         (implicit) pop and print each stack item, separated by newlines

->x,y{h=?#;puts t=h*x,y>1?[[h+(x<2?'':' '*(x-2)+h)]*(y-2),t]:p}

INPUT x,y
FOR i=1TO y
FOR j=1TO x
?i MOD y<2OR j MOD x<2;
NEXT
?
NEXT

? 5,3
-1 -1 -1 -1 -1
-1  0  0  0 -1
-1 -1 -1 -1 -1

INPUT x,y
SCREEN 9
FOR i=1TO y
FOR j=1TO x
PSET(j*3,i*3),i MOD y<2OR j MOD x<2
NEXT
NEXT

DECLARE @ INT=3,@y INT=5

PRINT REPLICATE(1,@)+ISNULL('
'+REPLICATE('1'+ISNULL(SPACE(@-2),'')+'1
',@y-2)+REPLICATE(1,@),'')

P3G$PG@PS@S$B$T1B@T1B$T1B@

P3  Paint current square with 3
G$P Get: sets $ from input P
G@P Get: sets @ from input P
S@  Subtract 1 from @
S$  Subtract 1 from $
B$  Brush $ more square[s]
T1  Turn 1 right angle clockwise
B@  Brush @ more square[s]
T1  Turn 1 right angle clockwise
B$  Brush $ more square[s]
T1  Turn 1 right angle clockwise
B@  Brush @ more square[s]

x0y9P3G$PG@PS@S$B$T1B@T1B$T1B@