How can I integrate a function and exclude a specific x-value?

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Karsten Gros 2017-1-31

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回答： Walter Roberson 2017-2-1

Hi, I have a question regarding the integralfunction. Let's say I want to integrate a function from a to b, but without the left border. Like if I have f(x)=1/(x-1), and I want to integrate f from 1 to 10, but at 1, there is a definition gap. Sorry for my bad english, I tried my best ;) Thanks in advance and best regards

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Answer 1

Walter Roberson 2017-2-1

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Calculate the next representable number and use it.

negative values, next larger value is

typecast(typecast(Value,'uint64') - 1 ,'double')

negative values, next smaller value is

typecast(typecast(Value,'uint64') + 1 ,'double')

positive values, next larger value is

typecast(typecast(Value,'uint64') + 1 ,'double')

positive values, next smaller value is

typecast(typecast(Value,'uint64') - 1 ,'double')

I tried with using multiplications and divisions with 1+eps and 1-eps but I ran into some problems due to round-off, and was having to start to use expressions like mean([v,v/(1+eps)]) . It was easier to be certain by switching representations.