@Markiyan Hirnyk Sir here am indicating my exact problem.. I am attaching worksheet here and problem is my last nested loop is not working neither it  picks above mentioned boundary conditions and initial condition.. So sir what u suggest me now can u help me in this regard. I will be very grateful..code_for_fdm.mw

@Markiyan Hirnyk Sorry to say sir but i dont know why you are so harsh to me. I have been helped by my one of friend from step 2 but uptill step 2 code is written by me. Now i dont know why you are again and again embracing me for what reason. Sir if i would know how to write perfect code then why should i post here for help. Am sorry if my words hurt you...

@Carl Love sure this is worksheet which you have already seen and infact you also helped me but now in plotting am not getting graph trytimg.mw 

thanks for helping me can you help me if i want to change my interval for example i have taken above code for inteval [0,1] x [0,1] but what if i have to take for interval [-1,1] x [-1,1]. 

I have tried but still not getting it my graphs shows only for interavl[-1,0] x [-1,0] not for [-1,1] x [-1,1]

please let me know what alternations i have to do with above code for this interval

thanks for helping me can you help me if i want to change my interval for example i have taken above code for inteval [0,1] x [0,1] but what if i have to take for interval [-1,1] x [-1,1]. 

I have tried but still not getting it my graphs shows only for interavl[-1,0] x [-1,0] not for [-1,1] x [-1,1]

please let me know what alternations i have to do with above code for this interval

please guys help me if u can i need this code its really important

thanks for your kind reply...

thanks for your kind reply...

@Carl Love thanks alot for your help but still i was not able so i tried something else and i got same results as you got command was same just after importing data i used L := convert(M, listlist) and then i used surfdata command and it worked. Once again thanks alot...:)

@Carl Love thanks alot for your help but still i was not able so i tried something else and i got same results as you got command was same just after importing data i used L := convert(M, listlist) and then i used surfdata command and it worked. Once again thanks alot...:)

@Carl Love this is txt file which I am importing from ImportData() command hmmm.txt 

and taking float[8](64 bit) and tab spacing stil getting error which i told you before. Now what you suggest

@Carl Love this is txt file which I am importing from ImportData() command hmmm.txt 

and taking float[8](64 bit) and tab spacing stil getting error which i told you before. Now what you suggest

@Carl Love again i have done as u said and when i enter float[4](32-bit) or float[8](64-bit) with Tab separated i got required matrix and when i go for command 

plots:-surfdata(M, 0.05 .. 0.85, 0.05 .. 0.85, labels = [t,x, U],axes = boxed, title = "Crank-Nicolson")

 it give me error "Error, (in plots/surfdata) incorrect format for input points" 

now what does this mean...???

@Carl Love again i have done as u said and when i enter float[4](32-bit) or float[8](64-bit) with Tab separated i got required matrix and when i go for command 

plots:-surfdata(M, 0.05 .. 0.85, 0.05 .. 0.85, labels = [t,x, U],axes = boxed, title = "Crank-Nicolson")

 it give me error "Error, (in plots/surfdata) incorrect format for input points" 

now what does this mean...???

@Carl Love as u are saying am doing same but whenever i enter command of ImportData() and after selecting file it ask me for format of file. If am not going for select file format option my maple stops it give me error and when i go for select file format option it directly gives me ImportMatrix option as u have seen in worksheet. Am using maple 13 so am not able to get it. worried alot