@dharr thankyou for your kind response i get your point

cgpt.mw this is code from chat gpt it also include errors

@acer the code is working for n=0..G where G is any number but when i take  G=infinity it is not evaluating taking alot of time summation.mw

@acer you are right i want to take values of x_i but after writing in this way still code is not working

Download Aexample.mw

@Carl Love 

@nm  this mark is check always again i am facing issue but it is only for some files not for all i 

@nm i am not editing while maple is runnig code , i want to edit when maple is ready but it does not let me. i can edit after restarting the file . and again while i am editing and evaluating it and when maple is ready again i want to edit it is edit able again i  have to restart the file

@acer the conotour plot at the end of the worksheet of approximate values and exact values are shown and both are similar i have just  one issue which is on exact y-axis is labelled to 0 to 0.9 and x axis to 0 to 1.0 but in approximate case it is different y axis= 1 to 7 and x axis to 1 to 11. i want y axis to be written u_1 , u_2,...,u_7 and x axis 0 to 1.0 in approximate contour plot. kindly help

@acer in listcontplot "contour plot" is perfect  but it is taking values of x-axis and y-axis by default i want to give values on my own i have tried one sequence command but there are mistakes again the contour plot is not similar  it is not taking all values of matrix i think kindly help. i am sharing picture

@acer Thank you so much for your detailed and insightful response to my question! Your explanation clarified a lot of the confusion I had, and your examples were incredibly helpful. I appreciate the time and effort you put into helping me out.

@acer can you help with the contour plot?

@acer Is there not any way to plot surface for approximate values generated from loop in maple? In your previous response you again made surface with use of exact surface. I want approximate surface without use of exact. I am attaching here a file in which approximate surface and exact surface are shown i want something like that

@acer do not merge both surfaces. Plot exact surface then plot approximate surface both different surfaces. After doing that make one 2d plot where approximate and exact values comparison can be made. But this 2d plot is not that important. The important is approximate surface and exact surface which is already ploted 

@mmcdara I've attached the file for your reference. The error graph is ploted correctly but i want surface 3d plot of approximate solution as surface 3d plot of exact solution which is already ploted in  the maple code file. 
 If possible, I'd like to see a 2D graph that compares the exact values with the approximate values obtained from the code. However, the most important aspect is getting the approximate 3D surface to work as intended.

Download DQMSixth_(2).mw