Is it possible to return multiple values from mysql function?

The correct way to do this would be using a stored procedure:

CREATE PROCEDURE stored_proc(IN arg1 INT, IN arg2 INT, OUT retVal1 FLOAT, OUT retVal2 FLOAT, OUT retVal3 FLOAT)

You can then assign the variables with

SELECT x*y INTO retVal1;
...

and call the stored procedure with @variables to access them:

CALL stored_proc(1, 2, @retVal1, @retVal2, @retVal3);

My dirty solution is: 1. Concatenating values in a string. 2 returns string. 3 Splits returned string to values. I assume that it is not elegant and I sure this have limitations but it works for simple cases

Also is necessary create the splitting function because Mysql has not this function:

First edit your function.

CREATE FUNCTION yourFunctionWith2valuesForReturning()
BEGIN
     DECLARE var1 VARCHAR(255);
     DECLARE var2 VARCHAR(255);

    // Your function logic here. Assign values to var1 and var2

    RETURN CONCAT_WS('|', var1, var2);
END

Now you can split your returned value calling this function:

CREATE FUNCTION SPLIT_STR(x VARCHAR(510), delim VARCHAR(12), pos INT) RETURNS VARCHAR(255) DETERMINISTIC
BEGIN
RETURN REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos),
       LENGTH(SUBSTRING_INDEX(x, delim, pos -1)) + 1),
       delim, '');
END

For getting the values

SET value1 = SPLIT_STR(returnedVAlue, '|', 1);
SET value2 = SPLIT_STR(returnedVAlue, '|', 2);

Notes:

You can use a string as delimiter, f.e: '|sep|' or another you want.

SPLIT_STR function is cortesy of http://blog.fedecarg.com/2009/02/22/mysql-split-string-function/

About splitting a string in mysql see also this question: Split Varchar into Character in MySQL

"MySQL stored function returns only one value" BUT, with a trick, it is possible to obtain multiple results from a function that can be used, AFTER its call, in other parts of the SQL code:

CREATE FUNCTION `return_multi`(
    `txt` VARCHAR(50)
)
RETURNS varcHAR(50)
LANGUAGE SQL
NOT DETERMINISTIC
NO SQL
SQL SECURITY DEFINER
COMMENT 'A trick to get multiple values ​​from a function'

BEGIN
set @return_multi_length=length(txt);
set @return_multi_upper=upper(txt);
set @return_multi_lower=lower(txt);
return concat(upper(substring(txt,1,1)),lower(substring(txt,2)));
END

Now call the function:

SELECT return_multi('vicTor') as RES;

Then get other values:

SELECT
 @return_multi_length as LEN
,@return_multi_upper AS UP
,@return_multi_lower AS LOW;

Just use a JSON return and put whatever you want in it.