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**Wayintense** Hello. Thank you in advance for any help you can offer. I'm working with afunction that relates flow and pressure. For simplicity, let’s say the function is P = A Q^2, where P is pressure, Q is flow, and A isconstant. This equation accuratelydescribes the behavior of a system when Q exceeds a certain value. Below this threshold, P is constant. For the systems I am now contemplating, Iknow what the threshold value of P is, but I don’t yet know A. So, right now, I don’t know the value of Qthat corresponds to the known pressure threshold.

Let’s say that Iknow that P can never be less than 80 and through experiments I learn that A = 5. In this case, I’ll be able write: P = 80 when Q < 4; P = 5 Q^2 when Q > = 4. While this notation may not comply withapplicable math notation standards, a reader would probably get the gist of what I’mtrying to say. (By the way, I would liketo know the technically correct way to express this conditional if somebodywould kindly show me.)

More immediately, I would liketo better understand the correct way to express the above equation when I don’t yetknow A and the value of Q that corresponds to the known minimum threshold ofP. For example: I want to write an expressionthat says P is equal to the greater of these two values: 80 or A Q^2. What is the correct notation to express this?

Thanks!