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Help with iteration in 'while' loop
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Hi,
I am trying to write an engine simulation program in C++ - please not that I have never done any programming.
I have attached what I have done so far which is a program that calculates the cylinder volume from a crank angle (theta). What I need now to do is use those iterations to find the pressure at each crank angle - the function is in the form of:
P(theta + dtheta) = P(theta) * (V(theta)/V(theta + dtheta))
ie the current pressure is found using the pressure from the previous iteration, the current volume and the previous volume.
How do I write program to use both the current and previous values for volume? Im sure it can be done, I just can't figure out how to do it.
Any help would be appreciated!
I am trying to write an engine simulation program in C++ - please not that I have never done any programming.
I have attached what I have done so far which is a program that calculates the cylinder volume from a crank angle (theta). What I need now to do is use those iterations to find the pressure at each crank angle - the function is in the form of:
P(theta + dtheta) = P(theta) * (V(theta)/V(theta + dtheta))
ie the current pressure is found using the pressure from the previous iteration, the current volume and the previous volume.
How do I write program to use both the current and previous values for volume? Im sure it can be done, I just can't figure out how to do it.
Any help would be appreciated!
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Join Date: Feb 2002
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It's 3 am here so I can't offer much assistance for the simple fact that I am having a hard time keeping my eyes open. But here is some food for thought until you get better replies: http://www.daniweb.com/forums/thread1734.html
Dani the Computer Science Gal 
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Follow my Twitter feed! twitter.com/DaniWeb
And if you're interested in Internet marketing there is twitter.com/DaniWebAds
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Join Date: May 2004
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Posting Whiz in Training
@cscgal
go to bed earlier!
You say you have never done any programming. This is not really that easy of a thing to do. Start out simple!
go to bed earlier!
You say you have never done any programming. This is not really that easy of a thing to do. Start out simple!
Yeah tell me about it!
Unfortunately I don't have any choice. I'm doing my final year project on engine simulations and I was under the naive impression that I would have a program to use! So now I have to write my own. :lol:
Unfortunately I don't have any choice. I'm doing my final year project on engine simulations and I was under the naive impression that I would have a program to use! So now I have to write my own. :lol:
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Join Date: May 2004
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Posting Whiz in Training
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Originally Posted by marceta
@cscgal
go to bed earlier!
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Join Date: May 2004
Posts: 95
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Junior Poster in Training
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Originally Posted by Jo_1660
...
How do I write program to use both the current and previous values for volume? Im sure it can be done, I just can't figure out how to do it.
...
It looks like you already have two, i.e. V and V2, but you're only using one of them. I'd rename V2 something more descriptive, like OldV or something, and make it so V has a value before you start the loop. The only addition to the loop would be to add a line at the start that says 'OldV = V;'--then you can do whatever you want with V in the loop body, since you've already stored the previous value. Once you've calculated a new value for V, you can use both the current and previous values as much as you want. OldV will only ever hold the most recent value of V.
Hope that helps.
--sg
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