@mmcdara 

Thank you very much for your help. I am a 23-year-old student from China. This solution obtained using maple will be used in my graduation thesis as a comparative solution for the correlation values of the response function obtained by the Monte Carlo method. Yours I was so touched by the help.

As you mentioned, I confused the variance with the second-order origin moment. In fact, I wanted to do parameter sensitivity analysis and get the functional relationship between the g function and thetas. Later, i will study how the uncertainty of thetas affects the g function.

It’s also worth mentioning that before you responded to my post, I was still reading your previous reply to another user (https://www.mapleprimes.com/questions/235988-How-Do-I-Solve- This-System-Of-4-Nonlinear), and try to find something I can use from it, haha, the reply you wrote on March 23, 2023 was viewed by me on March 4, 2024, It is also a kind of fate. Maybe my questions and your answers today will also help others in the future.

Thank you again for your reply, it gave me crucial help when I was in trouble. In addition, I really envy you for having such a strong technical ability.How can I become someone like you who has an outstanding ability and helps others?I feel like I have a lot to learn now。

I wish you good luck !!!

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