Happy that you enjoy our artithmetics :bigsmile:

Basically, what you could do is 10 deg incremental measurements 0-60 deg if that is enough in your opinion.

The easy way out is to do this for every 10 deg interval:

Gain 0 minus gain 10. This gives us the delta.

Divide delta with 2.

Add the half delta to Gain 10. This gives us the average Gain between 0 and 10.

Multiply this average with 10, as the interval between measurments is 10.

Repeat this between all measurements and incrementally add the results.

Then you get the area under the gain curve which could represent an acumulated persieved light reflection of the screen from 0-60 deg.

Custard, I thought excel had some tools for integrals but I cant find any. Can you suggest better, more accurate ways of estimate the integral of the curve based om measurements from mech?

there are some add ons for excel which caculate the area under the curve but i have not used them.

i have simply created the formula myself for one reading and then applied it to the rest.

with the data mech has provided and because we donot have equal intervals between measurements, the closest approximation that i can think of is that trapezoid rule again.

mech has provided readings at 30 and 60 degrees so calculating the values for total perceived light at these is fairly simple.

the 10 degree intervals are going to need more approximations and more calculations..

mech has provided readings for 15, 20, 30, 45 and 60.

so for the 10 degree intervals we are missing 10, 40 and 50.

if we assume a linear change between each interval:

then for 10 degrees we can approximate total gain as 2/3 of the total gain at 15.

the calculation would be:

[(gain at 0 - gain at 15) x 1/3] + gain value at 15 = gain value at 10 degrees

total gain at 10 = (gain value at 0 + gain value at 10)/2 x 10 (trapezoid rule)

for 40 degrees, total gain can be appproximated as total gain at 30 degrees plus 2/3 of the total gain difference between 30 and 45 degrees.

for 50 degrees, total gain can be approximated as total gain at 45 degrees plus 1/3 of the difference between 45 degrees and 60 degrees.

robert - what set of values are you using to calculate your total gain values for -75 to 75. i think the 250 watt readings are better to use than the 1000 watt readings in this instance.