X = [X1 X2]; - Please Explain (2024)

... more than you wanted to know ;-)

• In the case where x is an empty numeric or char array (not string or logical) of no more than 2 dimensions, then the value 1 would be converted to the same class as the input x and the resulting 1 would be assigned to become the new value of x. conversion to char is by applying char() which gives the corresponding UNICODE character positions -- for example char(1) is UNICODE U+0001 and not '1'
• In the case where x is an empty logical array of no more than 2 dimensions, then x would be assigned double precision 1 (the 1 would not be converted to logical)
• In the case where x is the 1 x 0 empty string array (no other size of empty), then the output would be "1" -- string() applied to the constant 1. Here the "1" is the character for the digit 1, U+0031, not by looking up as a binary code position, not U+0001 . conversion to string formats numeric into text; conversion to char() does not
• In the case where x is an empty string array that is not 1 x 0, then the operation is an error
• in the case where x is an empty numeric array that is not double precision, or is a char array, or logical, or string, and the array has more than 2 dimensions, then the operation is an error -- for example, [zeros(256,512,11,0,19,'single'), 1] is an error
• In the case where x is an empty double precision array of any dimension, then x would be assigned double precision 1 -- for example, [zeros(256,512,11,0,19), 1] is valid -- but only if x is double precision
• In the case where x is a numeric or char (not logical or string) row vector (exactly one row, any number of columns, no non-trivial hyperdimensions), then the value 1 would be converted to the same class as x and added to the end of the row and the output would be the input x with the converted 1 appended to the single row. conversion to char is by applying char() which gives the corresponding UNICODE character positions -- for example char(1) is UNICODE U+0001 and not '1'
• In the case where x is a logical vector (exactly one row, any number of columns, no non-trivial hyperdimensions), then x will be converted to a double precision row, and numeric 1 will be appened to that row, and the output will be a double precision row
• In the case where x is a string() vector (exactly one row, any number of colums, no non-trivial hyperdimensions), then the 1 will have string() applied to it, producing "1", and that "1" will be appended to the end of the row vector as a new element. ["abc" 1] will result in ["abc" "1"], not in "abc1" -- see the string + operator to merge strings. Here the "1" is the character for the digit 1, U+0031, not by looking up as a binary code position, not U+0001 . conversion to string formats numeric into text; conversion to char() does not
• In the case where x is not numeric or char or logical or strign, the results are defined by the class methods; the results are well-defined for some classes, but is an error for other classes