what is the meaning of following code?

function [s_box_out] = s_box_fun(s_box_in)

rw = size(s_box_in, 1);

cl = size(s_box_in, 2);

s_box_in = reshape(s_box_in', rw*cl, 1)';

s_box_table = [ 99,124,119,123,242,107,111,197,48,1,103,43,254,215,171,118 ...

202,130,201,125,250,89,71,240,173,212,162,175,156,164,114,192 ...

183,253,147,38,54,63,247,204,52,165,229,241,113,216,49,21 ...

4,199,35,195,24,150,5,154,7,18,128,226,235,39,178,117 ...

9,131,44,26,27,110,90,160,82,59,214,179,41,227,47,132 ...

83,209,0,237,32,252,177,91,106,203,190,57,74,76,88,207 ...

208,239,170,251,67,77,51,133,69,249,2,127,80,60,159,168 ...

81,163,64,143,146,157,56,245,188,182,218,33,16,255,243,210 ...

205,12,19,236,95,151,68,23,196,167,126,61,100,93,25,115 ...

96,129,79,220,34,42,144,136,70,238,184,20,222,94,11,219 ...

224,50,58,10,73,6,36,92,194,211,172,98,145,149,228,121 ...

231,200,55,109,141,213,78,169,108,86,244,234,101,122,174,8 ...

186,120,37,46,28,166,180,198,232,221,116,31,75,189,139,138 ...

112,62,181,102,72,3,246,14,97,53,87,185,134,193,29,158 ...

225,248,152,17,105,217,142,148,155,30,135,233,206,85,40,223 ...

140,161,137,13,191,230,66,104,65,153,45,15,176,84,187,22];

s_box_out = s_box_table(s_box_in + 1);

s_box_out = reshape(s_box_out', cl, rw)';

Answer 1

[Adam Danz]

s_box_in is a matrix, presumably of positive, non-zero integers such as [5 2 99 43 100, ...]

s_box_table is a hard-coded list of values stored in the function.

s_box_out is a matrix that appears to be the same size as the input-transposed except its values are pulled from the s_box_table vector according to the indicies supplied in the input.

[Md.Simul Hasan Talukder]

Thank you