Why in the Test Assessment I can't use the '==' operator to compare expressions of type real_T within the 'verify' operator?

When I run a test in which I use a 'verify' operator in a test assessment I obtain the following warning:

"The use of the '==' operator to compare expressions of type real_T within the 'verify' operator may produce unexpected results. Step 'step_0_6605' in Test Sequence 'WiperFunctionSWC_PIL_NominalWorkingConditions/Test Assessment': verify(WiperSpeed==0)"

While when I use an 'assert' operator it works fine.

[Image Analyst]

What is a "Real_T" data type? Why not just use a normal double variable for WiperSpeed? Does it need to be that Real_T data type?

Answer 1

[Gyan Vaibhav]

Hi Domenico,

The warning you encountered is not related to the type of variable you are using, “real_T”, but rather it is related to the precision of floating-point numbers. The following documentation links for both the “verify” and “assert” functions emphasizes the importance of using a threshold when working with floating point numbers:

https://in.mathworks.com/help/sltest/ref/verify.html

https://in.mathworks.com/help/sltest/ref/assert.html

To address this warning, you can use the following workaround:

thres = 0.001; % Set your desired threshold 
verify(abs(WiperSpeed - 0) < thres) 

By comparing the absolute difference between “WiperSpeed” and 0 against the threshold in the “verify” statement, you should be able to avoid the warning. I hope this explanation helps.