thank you so much for optimization procedure.
However, there was a problem of defining one variable which needs to be multiplied by 60 (it was typo in rouben's code). see my reply to rouben:
Everything is find with your answer except one mistake in replacing t with t_number. in my code, t=t_number[i] *60 (which is change of minutes to seconds) however, in your code, you didnt use 60. However, when I try to add 60 in your code, the solution would be different and it is equal to 0.0023.
So, when I multiply t_number by 60, the optimization code did not give the correct results (it should be 0.0023).
How can I correct that procedure?
Thank you so much for your help in advance