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Return logged magnetic field data from iOS sensor


[log, timestamp] = magfieldlog(m)



[log, timestamp] = magfieldlog(m) returns the magnetic field log, where m is the name of the mobiledev object that acquires the sensor data, log is an [mx3] matrix containing magnetic field data points, and timestamp is an [mx1] vector of timestamps.


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This example assumes that you have already installed and set up MATLAB® Mobile™ on your iOS device and connected it to your computer running MATLAB. For information about these steps, see Get Started with iOS Sensors.

Start MATLAB Mobile on your iOS device.

On the Sensors screen, tap the Magnetic Field sensor.

Place the device where you want to get the sensor data.

On your computer, create a mobiledev object, m, in MATLAB.

m = mobiledev

Begin logging data by enabling the Logging property.

m.Logging = 1

This action starts the transmitting of data from all selected sensors. You can also start transmission by tapping the Start button in MATLAB Mobile.

Get the logged magnetic field data.

[mf, t] = magfieldlog(m)

This returns the magnetic field log, where mf contains the three data points in X, Y, and Z coordinates, in microtesla.

See Device Orientation for a diagram showing the X, Y, and Z axes relative to the device.

Output Arguments

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Name of variable for magnetic field log data, returned as an [mx3] matrix of data points from the Magnetic Field sensor on the iOS device. The three data points are the magnetic field reading in X, Y, and Z coordinates, in microtesla.

Magnetic field is defined in relation to the X, Y and Z axes. If you place the device face-up on a table, the positive X-axis extends out of the right side of the device, positive Y-axis extends out of the top side, and the positive Z-axis extends out of the front face of the device. This is independent of the orientation of the device.

Name of variable for timestamp, returned as an [mx1] vector of timestamps from the Magnetic Field sensor on the iOS device. Time is in seconds, relative to the InitialTimestamp property.

Introduced in R2015a