Logarithmic X axis scale for frequency response possible?

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Posted by TAJ on 27th March 2013
I would like to use RGraph to build a little audio related app that needs an output graph. I was trying to determine if there is an attribute to set the x-axis to use a logarithmic scale as in a frequency response graph, but I could see anything in the documentation. Or perhaps there is some other way to tackle the problem?

On this random web page I found, there is an example of what I would try to produce: stackoverflow.com/questions/7793330/straightening-amplitude-frequency-response-graph-after-fft

Is that possible with RGraph?
Posted by RGraph support on 28th March 2013
Hi there,

I think it should be possible. You just need to set the chart.xmax to say 5 and then you can control the labels that are displayed with chart.labels. Though you may need to use the drawing API X axis object for the X axis. Eg:

jsfiddle.net/rgraph/7KJZj/


Richard, RGraph Support
Posted by Enter your name... on 28th March 2013
Okay thanks, I played with that for a bit and I could make it work to a degree, but the tick marks and grid lines and so forth looked like they'd be a lot of work to force to cooperate in that approach.

What I was hoping for, and you could take this as a feature request, was what I had used previously in the Flex chart library. There was a property you could set that controlled the numerical scale of each axis and it applied to the labels, the gridlines, the tick marks, etc.

Here's maybe a better visual example of what I'm trying to do. linear y scale, log x scale: artsites.ucsc.edu/ems/Music/tech_background/TE-02/AcNumbers/Image1.gif

..TJ
Posted by RGraph support on 29th March 2013
Hi there,

The grid doesn't do anything like that. To acheive it it would not be insignificant - you'd have to turn off the grid entirely and do it yourself. Though that in itself would not be simple as there's no "ongrid" event.



Richard, RGraph Support

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