Need AFL for this strategy!!!

[msieee]

please help me i need AFL for the following.

my strategy with ADX

Buy signal when
1. D+ > D-
2. D+ > 20
3. ADX > 20
4. ADX in upward

i found logic for the first 3 bt can't able to code the last one. Please help

 

[msieee]

4. ADX(14)>Ref(ADX(14), -1)

thanks dude then is this below right code

Buy = (PDI(Range)> MDI(Range)) AND PDI(range)>20 AND ADX(range)>20 AND ADX(14)>Ref(ADX(14), -1);