Dear all,

   I first thank Mr. Clayworth for giving me  many helpful suggestions. But, I have not solve the problem of smoothnes when plotting figures in Maple 11.  I do not know how to set the numpoint or grid sizes. In Maple 10,　I just fix the numpoints very  high to get smoothness.  In fact, now I can not obtain ideal figures using Maple 11. That makes me feel puzzled about  this software. I hope soemone can help to solve this problem throughly.  Thanks a lot !

Download 7745_1.eps
View file detailsDownload 7745_2.eps
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The attached files are the figures: Fig.1 , Fig.2 plotted by Maple 10 and Maple 11 respectively. 

I am grateful to Prof. Clayworth for kindly help. But I only have Maple 10 .  I have searched help page for realize it. But I failed. Could you know how to do it with Maple 10 ? Thank you very much !

Dear Sir/Madam, I have just resolved my problem. The problem results from the calculation scheme. In other words, the term (s(t)-s(xi))/(t-xi) can not be identified by computer when t=xi. Thanks all people, especially Jacques and Doug, who give me many helpful suggestions. Best wishes to all!

Dear Sir/Madam, I am grateful to Jacques and Doug for many help. According to their suggestions, I have revised the Maple codes, but the problem:'Float undefined' has not been resolved. I post my question enclosed in pdf file and Maple file in detail again. This question relates to iterations in ODE or integro-differential equations. Now I do not know how to handle this problem. Please help me! Thanks a lot ! Download 7745_question.pdf
View file details Download 7745_Float undefined.mws
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I would like to express my gratitude to Jacques and Doug for great help. You help me to find where problems come from. The term 'h=0.00000001' in g1 actually is used to approximate the derivative 'diff(s(xi),xi)'. In fact, in original form of g1, the term '(s(xi+h)-s(xi-h))/2/h' should be 'diff(s(xi),xi)'. Why does this method for approximating the first derivative lead to this problem? Thank you very much agian!