Thank you very much for your response.

The relationship of y to x in the y=mx+c is as follows:
y=0.065+0.805x
y=0.400-x
x=0.133+0.600y

Also, while the points at which these lines intersect with the human eye
response curve is not known, the general bounds are. This gives the following
coordinates of the bounds:
x1,y1 = 0, 0.065
x2,y2 = 0.185596, 0.214404
x3,y3 = 0.233125, 0.166875
x4,y4 = 0.133, 0

How can these be used to set up a formula to see if my measurements fall
within these bounds?
--
Mukesh


"Bernie Deitrick" wrote:

Mukesh,

You cannot do this with worksheet functions for any group of four functions, unless your know more
about how your y value should relate to the other functions. For example, if it should be greater
than the first, less than the second, less than the third, and greater than the fourth, for any
given x value, then you could reliably say when it will fall in that area. You may need to make a
truth table for various X ranges, and then compare the results of the various comparisons with the
values stored in the truth table.

HTH,
Bernie
MS Excel MVP


"Mukesh" wrote in message
...
In Excel 2000 and Excel 2003, I am trying to validate if specific (x,y)
coordinates fall within the area bounded by 4 intersecting curves with
equations "y=f(x)", and am looking for help to set this up. I have tried the
normal logic of IF, AND, and OR, but have not been successful at all.

Of the four functions of the type "y=f(x)". the fourth one is the locus of
the human eye response to colors, and is a very complex function. The others
are more like "y = mx+c". Since the complex function is representing the
boundary of an instrument's data output, the data will always be bounded on
that side. I am currently more concerned with the first 3 equations of the
first order, and would just like to ensure that my data points are within
their bounds.

Has anyone ever tried this in Excel, or am I the first one to venture into
this area?

--
Mukesh