@tomleslie 

Dear Tomleslie, 

Your suggestion is very apt. Apologies for my question not being quite clear. 

Thank you,

Omkar

@Carl Love 

Hi Carl,

This is great. It works really well. Thank you.

Omkar

@Carl Love 

Hi Carl,

Thank you for the reply. Sorry, there was a typo in my earlier query. Your confusion is justified.

I need to select a root where function value g(x, a) --- another function --- is positive. It would be nice if I can verify this condition with a single command that will substitute all roots and filter the ones that give positive output.

For further clarity, let me write down a sample problem:

1. f(x,a) and g(x,a) are given.

2. Solve f(x,a)=0 for all possible values of x.

3. Filter the set of roots to keep only real roots. 

3. Substitute the filtered set of roots into g(x, a) and filter the set further by keeping only those roots for which g(x,a)>0.

4. Print the set of roots. 

Regards,

Omkar