chart for a range of numbers

**jimminy121212** · 03-22-2009, 10:31 PM

Hiya, I have what must be an easy question, but I'm new to charting in excel.

I want a simple XY axis chart that will show how the value of the numbers on the Y axis are effected by the changing value of the X axis as it goes from one value to another.

The value on the Y is arrived at by solving a rather complicated equation that uses the range of values I would put on the X axis. Or simply, in my chart I want to show how the capacity of a roadway is effected by different car following distances, so if on my X axis I have a range from 10' to 50', the chart will show how this effects the capacity of the roadway for the values between 10' and 50'.

so what I have is a cell that has a variable for me to input the car-following distance (for the X axis) and another cell that shows the result of the calculation (which would go on the Y axis) but I don't know how to tell excel to make me a chart that would show the result for a range of distances, say from 10' to 50'.

I imagine this will be curve that descends from left to right as the input value (distance between cars) gets larger.

Can I tell tell excel to show on the chart all the results for a range of values? I can easily plot this out manually, but it seems like something excel would do easily, though I'm stumped as to how.

**shg** · 03-22-2009, 10:41 PM

Welcome to the forum.

Post a workbook and explain in context.

**jimminy121212** · 03-23-2009, 01:27 AM

Ok, here it is.

You'll see a list of variables with placeholder numbers that I would like to set ranges for to make comparisons. The X axis might be N or L or any one of those variables, but the Y axis value will be taken from the result shown below, cars per hour per lane.

Thanks.

**shg** · 03-23-2009, 11:11 AM

I don't see how you'd want to chart this. You have five variables, four of which are fixed for any given plot, and the remaining one varies. That's easy enough, if a little messy. You could solve for the derivatives (d capacity / d N, d capacity / d V, etc.).

BTW, the numbers confuse me. Shouldn't the platoon spacing be larger than the inter-vehicle spacing? It seems to me like the capacity formula should be

=5280 * N * V / (N * L + (N - 1) * S + F)

**jimminy121212** · 03-24-2009, 12:21 AM

Thanks for the reply. Yes, the platoon spacing would be a higher number if this were an actual test set, but it isn't.

You're right, the equation appears to be flawed, though now that I changed it, I can't see what the difference is. Be that as it may, I'm curious to know why it would be messy?

Also, I'm not sure what you mean by solving for derivatives. But if there's a better way to show this than the way I'm shooting at, I'm all ears.

Thanks again.