Calculating Gain: Inputting a value of 13 needs to generate 9000....

[s8lam]

Hi All,

I am struggling to figure out a working calculation for gain (feel free to tell me the correct terminology, it's just how I understand it).

Problem:

I am writing a software program that needs to convert an input value to a scaled output value over a range between 13(min value) and 1300(max value).
So:
Inputting a value of 13 needs to generate 9000.
inputting a value of 1300 needs to generate 0 (If zero is not possible, a value of 100 would work).

Normally, to calculate this I would divide the input by the required output to generate a gain (13/9000=0.00144444444444444444444444444444), therefore dividing the input number by the gain would generate the correct output, and a single gain works across the whole scale.

However, in the above case this does not work as the output needs to decrease as the input increases.
so:
13/0.00144444444444444444444444444444= 9000 (correct)
13000/0.00144444444444444444444444444444= 9000000 (incorrect, the gain for this needs to be 100/1300 = 0.07692307692307692307692307692308 (using 100 instead of zero)

Any ideas please?

Thanks,
Steve

 

[Deleted member 4993]

Hi All,

I am struggling to figure out a working calculation for gain (feel free to tell me the correct terminology, it's just how I understand it).

Problem:

I am writing a software program that needs to convert an input value to a scaled output value over a range between 13(min value) and 1300(max value).
So:
Inputting a value of 13 needs to generate 9000.
inputting a value of 1300 needs to generate 0 (If zero is not possible, a value of 100 would work).

Normally, to calculate this I would divide the input by the required output to generate a gain (13/9000=0.00144444444444444444444444444444), therefore dividing the input number by the gain would generate the correct output, and a single gain works across the whole scale.

However, in the above case this does not work as the output needs to decrease as the input increases.
so:
13/0.00144444444444444444444444444444= 9000 (correct)
13000/0.00144444444444444444444444444444= 9000000 (incorrect, the gain for this needs to be 100/1300 = 0.07692307692307692307692307692308 (using 100 instead of zero)

Any ideas please?

Thanks,
Steve

Slope = (1300 - 13)/(0- 9000) = -1287/9000 = -0.143

 

[s8lam]

Brilliant, I'll give it a go tomorrow.

Thanks very much

 

[stapel]

I am writing a software program that needs to convert an input value to a scaled output value over a range between 13(min value) and 1300(max value).
So:
Inputting a value of 13 needs to generate 9000.
inputting a value of 1300 needs to generate 0 (If zero is not possible, a value of 100 would work)....

What are the instructions for this exercise? What sort of model are you supposed to be finding? Linear (as the previous helper guessed)? Logarithmic? Exponential? What is your data set? And so forth.

Please be complete. Thank you!