Strange questions about convergence

To understand this issue, one needs a deep understanding of algorithms; I can only provide some simple explanations, and they might not be entirely accurate. I hope those with more expertise can correct me! Some better algorithms, such as the simultaneous correction method and homotopic iteration, are fast in terms of computation speed, but one problem they cannot solve is the initial value problem; inaccuracies in the initial values often lead to non-convergence. If the convergence error decreases step by step, it is possible to increase the number of iterations to achieve convergence, but this is not always the case. Currently, there are two ways to address this problem: 1) Change the initial value. This requires chemical engineering knowledge; you need to accurately estimate various initial values. 2) Change the algorithm. A specific algorithm is chosen for each model to achieve optimal convergence. The above two points are merely theoretical; I have written a short guide that can be used as a reference for setting initial values: http://bbs.hcbbs.com/thread-430336-1-1.html. It’s just my humble effort – I really hope to get some points for this! I’m about to move up to third grade!

I have an idea: maybe each time you adjust the program, you don’t initialize it, but instead continue working with the results from the previous run. After making many adjustments, you end up performing many calculations in a row. Once convergence is achieved, the results are saved, but when the program is run again, it starts calculating from those initial values again. Perhaps those initial values aren’t very appropriate, which is why convergence doesn’t occur. The reason convergence was achieved earlier was that each time, the calculations were continued based on the results from the previous run. That’s my theory. The original poster could try running the program after initialization to see if convergence still occurs; then, after saving the results and running the program again, check whether this issue persists.

I agree with what was said on the third floor; I think that if the initial values and convergence parameters are not changed, the results obtained by starting the calculations from scratch each time should be the same

Opening the APW file should display the calculation results from your last run. Try opening the APW file.

Well, then how do we initialize the values? :(

On the main menu, there is a blue triangle with its top corner pointing to the left; in front of the triangle, there is also a vertical icon. (I still don’t know how to send pictures... Please give me some advice.)

Thank you! Mine is just black. With a threaded reply, you can attach files and thus include images; with a quick reply, images cannot be attached :)

I have another question: where can I change the number of iterations? In some cases, 25 times might be too few; in PROII, I sometimes have to run it several times before it’s considered complete. It seems like this isn’t possible in A+

Make the modification under ma*amum iterations in block→convergence→basic. Good luck~~

I think that if the initial values and convergence parameters are not changed, the results obtained by starting the calculations from scratch each time should be the same

So does that mean the result calculated using the previous convergence result is incorrect? Then why does the program default to checking the option for using the previous result? What principle is responsible for the fact that the final result of such calculations is not valid?

I’ve encountered this problem too; there really is no good solution!