Excel spreadsheet to interpolate air specific heat capacity Cp from temperature table

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Homework Statement



using the table of values supplied (a pdf document), construct an excel spreadsheet wherein a value can be input from 200-2250 and output will be air's specific heat capacity at that temperature.

Homework Equations


Cp= H2-H1/T2-T1


The Attempt at a Solution



I have completed most things, I am just having issue where an exact value is entered on the temperature table, ie 200 has a value for H, and as such my formula input in both cells which is designed to essentially round down or up from the value selects the same values for Temperature and thus divides by zero.

I am currently attempting to input an If statement into the cell containing the upper (T2) value, but containing too many arguments.

This is the statement i have been using to calculate temperature for the upper:

=SMALL($D$18:$D$138,COUNTIF($D$18:$D$138,"<"&M21)+1)

inputting an if function I thought of but it ended up containing too many arguments (essentially if A1=A2 then above formula acts as if M21 was added with +1 to its cell).

So is there a way to simplify?

Or should i make cell 2 conditional upon cell 1 and try and make it select the next sequential cell automatically?

How do I do that?

Any and all help is appreciated.
 

Discussion

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Hey StephenQueen and welcome to the forums.

The simplest If statement is just =IF(statement,true-value,false-value). You can nest the if statements within each other to do more complex statements.

For example =IF(A1>B1,1,0) would return 1 if A1>B1 and 0 otherwise.

Can you outline in the simplest manner what your conditions are? If you can provide really simple pseudo code and all the checks you need to do, then we can give more specific advice.
 
My conditions are to check for the closest upper value within an array of cells compared with the 'temperature' input, and correspond with the output being that closest temperature.

What I'm trying to do is have the cell check if its value is the same as that of another, and if so, to change its output to the next highest integer.

I think I may have solved my problem though- I don't think i may need the if operator now, just changing the upper check so that it always adds 1 to the value of temperature. Seeing as it will always tend towards that value anyway, it changes little.


I think i did it.