Topic: Display problem with function containing (-1)^x

Sample attached containing a function like f(x)(-1)^x.

It will not display unless range and step are used to force integer arguments, because non-integer powers of -1 are complex, so that's expected.

But with integer arguments the function displays fine only when the range is fully visible. When the range is beyond the visible portion of the x axis, none of the function displays. I'm not sure if this is intended by design.

Post's attachments

Attachment icon Display (-1)^x.grf 926 b, 387 downloads since 2010-07-09 

Re: Display problem with function containing (-1)^x

To be honest I don't remember why the end of the axis range has any effect on this. It looks a little strange. Some of it were already improved and I just went through the code and made sure the current axis range doesn't interfere with the use of integer arguments.

You can find it in the beta version of Graph 4.4 at http://padowan.dk/graph/DownloadBeta.php

Re: Display problem with function containing (-1)^x

The disappearing display may be symptomatic only for functions which have no value when arguments are not integers. The problem appears to be that integer arguments are not being provided to the function when they should be. The range extending beyond the visible x axis may not be required for this to occur.

The attached example, is a function which returns an integer value for an integer argument but is also defined for non-integer arguments. It is graphed for different integer ranges and can be seen graphing values for non-integer arguments, though the table values are correct. The displayed values of the functions change when the graph is scrolled horizontally in small increments. This is particularly noticeable at  the lowest point of the V.

Post's attachments

Attachment icon Integer values of range.grf 1.67 kb, 373 downloads since 2010-07-11 

Re: Display problem with function containing (-1)^x

Did you try the beta version of Graph 4.4?

Re: Display problem with function containing (-1)^x

I have been very pleased with 4.3 and had no need to move up before this (kudos, Ivan!). These days I'm frequently working with integer arguments so I guess it's time to make the move to 4.4 beta. What is the minimum O/S requirement?

Re: Display problem with function containing (-1)^x

Never mind - got it from FAQ. Now I remember why I'm not testing the beta yet: I'm using graph on an old W98SE station!

Re: Display problem with function containing (-1)^x

Graph 4.4 requires at least Windows 2000. Windows 98 is unfortunately no longer supported. It actually surprises me that Windows 98 is still in use.

Re: Display problem with function containing (-1)^x

Yes, I'm a little embarrassed to admit it, and I do have newer hardware and several XP Pro licenses around here. It's just that I have so much history on this box I hate to part with it. But reasons to upgrade are starting to accumulate. I won't attach a graph. smile