MATLAB: Undefined function ‘im2single’ for input arguments of type ‘uint8’

I get error message

Undefined function 'im2single' for input arguments of type 'uint8'.

Any idea?

ver :

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MATLAB Version: 9.0.0.341360 (R2016a)

MATLAB License Number: 847814

Operating System: Microsoft Windows 7 Professionnel N Version 6.1 (Build 7601: Service Pack 1)

Java Version: Java 1.7.0_60-b19 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode

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MATLAB Version 9.0 (R2016a)

Curve Fitting Toolbox Version 3.5.3 (R2016a)

Image Processing Toolbox Version 9.4 (R2016a)

Signal Processing Toolbox Version 7.2 (R2016a)