extracting values from two variables using programming

[YA_10963798]

I need to find q1 which is basically the values of qcza( known variable) qcza is the resistance in known depth [z]. 

q1 is equal to qcza when the depth is between 0.7D<z< 4D when D=0.4 and it has always to choose the minimum value until there is smaller value

 

[Werner_E]

Isn't this the same question as here: https://community.ptc.com/t5/Mathcad/find-value-from-matrix/m-p/934126/highlight/true#M210569

(If not, please explain the difference).

Strange that this thread here show a time stamp prior to the one in the referenced thread, but it did not show up here in the Mathcad forum until now!!?
Maybe a kind mod has moved it over to here - where did you post this in first place?