how to set xAxis pointInterval(update: tickInterval) in highcharts - highcharts

Question

I want to set the xAxis pointInterval in highstock.
I'm formatting the xAxis:
xAxis: {
type: 'datetime',
labels: {
formatter: function () {
var someDate = new Date(this.value);
return Myfunction(new Date(someDate));
}
}
},
I have searched and found some ways but they were not worked for me! In order to set the pointInterval for a day( 24 * 3600 * 1000 // one day ) I set it when I was adding a series:
chart.addSeries({
name: my name,
data: my data,
id: my id,
type: 'spline',
pointStart:start date,
pointInterval: 24 * 3600 * 1000 // one day
});
but It didn't work. so I tried to do sth else:
plotOptions: {
spline: {
pointStart: start date,
pointInterval: 24 * 3600 * 1000 // one day
}
},
It also did not work.
I've tested:
chart.xAxis[0].setCategories([data])
but this code makes the CPU working a lot and the browser crashes!
Actually I've seen these examples. but when I try them they aren't useful!
http://jsfiddle.net/larsenmtl/SJSwt/1/
http://jsfiddle.net/gh/get/jquery/1.7.2/highslide-software/highcharts.com/tree/master/samples/highcharts/xaxis/labels-overflow/
Please help me!
Thank you
UPDATE: my data is formatted like this:
series: [{
data: [
[Date.UTC(2010, 0, 1), 29.9],
[Date.UTC(2010, 0, 2), 71.5],
[Date.UTC(2010, 0, 3), 106.4],
e.g. jsfiddle.net/bahar_Agi/J6H7f

Answer 1

Pointstart only really applies if you haven't specified x values for your data or are using categories. As you have specified x and y values for each point, you should use the tickInterval option on the x-axis like this:
xAxis: {
type: 'datetime',
labels: {
style: {
fontFamily: 'Tahoma'
},
rotation: -45
},
tickInterval: 24 * 3600 * 1000
},
The highcharts api guide mentions this for datetime axis: http://api.highcharts.com/highcharts#xAxis.tickInterval
In this example, I set the tickInterval to 1 day, which may be a bit too small for your data, but you can change that to whatever interval you want.

Answer 2

I think you want to use tickInterval option for xAxis, see:
xAxis: {
tickInterval: 24 * 3600 * 1000,
type: 'datetime',
labels: {
style: {
fontFamily: 'Tahoma'
},
rotation: -45
}
},
jsFiddle: http://jsfiddle.net/J6H7f/1/