How to enable Automatic Memory Management in Oracle 11G

How to enable Automatic Memory Management in Oracle 11G
1. Set MEMORY_TARGET as (memory_target = sga_target + max(pga_aggregate_target, maximum PGA allocated))
        ALTER SYSTEM SET MEMORY_TARGET = mM SCOPE = SPFILE;
2. Set parameter MEMORY_MAX_TARGET
        ALTER SYSTEM SET MEMORY_MAX_TARGET = nM SCOPE = SPFILE;
Note:   1. n > m
                2. if don't specify MEMORY_TARGET it sets to zero by default
                        and you can manipulate its value dynamicaly not exceeding MEMORY_MAX_TARGET
3. Set SGA_TARGET to zero
        ALTER SYSTEM SET SGA_TARGET = 0;
4. Set PGA_AGGREGATE_TARGET to zero
        ALTER SYSTEM SET PGA_AGGREGATE_TARGET = 0;
       
Note:
The preceding steps instruct you to set SGA_TARGET and PGA_AGGREGATE_TARGET to zero
so that the sizes of the SGA and instance PGA are tuned up and down as required,
without restrictions. You can omit the statements that set these parameter values to zero
and leave either or both of the values as positive numbers.
In this case, the values act as minimum values for the sizes of the SGA or instance PGA.