How to view value of node output? My current situation with Cycles nodes:
I'm trying to make particles turn from dark to bright in time. So the Particle Info node has output "Age". But Sticking that value into Mix node produces no or complete change in the mix. So I start trying to math-fix it. I found out I can divide the value and that makes it work, but the particles turn from one to the other too fast, I can only control how far off they suddenly change.

How am I supposed to understand the values? Is trial and error the only way?
The Age output of the Particle Info node is measured in frames (like the particle setting itself). So the simplest way of normalizing the value (get it into 0..1 range) is to divide by the Life setting of the particle system:


You can also divide by the Lifetime output of Particle Info, giving the relative age for each particle:


Note however that the Lifetime value can vary for each particle depending on the Random factor in particle settings:

Divide by constant:



Divide by Lifetime (with Random = 0.75)