Chart中数据类型的运算规则

我在StateFlow的chart有限状态机中，写下如下命令：

Rail_numRev=uint32(Rail_numRev+1*Epm_nEng10ms);

其中，Rail_numRev定义为uint32，Epm_nEng10ms定义为fidxt(1,16,2^-1,0)数据类型，请问Rail_numRev+1*Epm_nEng10ms后的数据类型为什么？

Answer 1

[Zuber]

Hi,

I understand that you want to know the datatype of ‘Rail_numRev+1*Epm_nEng10ms’ in the following equation:-

Rail_numRev=uint32(Rail_numRev+1*Epm_nEng10ms);

Since ‘Rail_numRev’ is defined as uint32, it is an unsigned 32-bit integer. The data type of ‘Epm_nEng10ms’ is defined using the ‘fidxt’ function. Although the ‘fidxt’ function is not explicitly defined in the code you have shared, but seeing its definition it appears that it returns a fixed-point data type with word length of 16 bit. Assuming that ‘fidxt’ returns a fixed-point data type, then ‘Epm_nEng10ms’ would also be a 16-bit word length fixed-point data type.

When ‘Rail_numRev’ (an unsigned integer) is added to ‘1*Epm_nEng10ms’ (a fixed-point data type) the result should be a fixed-point data type. This can be verified by using ‘class’ function as follows:-

class(Rail_numRev+1*Epm_nEng10ms);

For more information on identifying the data type of a variable, please refer to the following documentation link:-

https://www.mathworks.com/help/matlab/ref/class.html

I hope it resolves your query.

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>> class(Rail_numRev+1*Epm_nEng10ms)

未定义与 'Simulink.Signal' 类型的输入参数相对应的运算符 '*'。

>> Rail_numRev+Epm_nEng10ms

未定义与 'Simulink.Signal' 类型的输入参数相对应的运算符 '+'。

[萍]

通过仿真测试，发送Rail_numRev的值只能累加到2，从而判定Rail_numRev+1*Epm_nEng10ms的数据类型为fidxt(1,32,2^-30,0)，但是不清楚为啥数据类型会变成这样，能否通过什么设置，不允许整数与定点数之间进行运算（报错）。

[Zuber]

In my answer, I assumed that fidxt() is an user-defined function since there is no such function in documentation. However, if it is a typo and you are using fixdt() function, it will return a Simulink.NumericType object.

In such a case, MATLAB will throw error on adding 'Rail_numRev' with '1*Epm_nEng10ms' since mathematical operations are not supported for operands of type 'Simulink.NumericType'. Please inform about your MATLAB version and system information, and if possible, upload a screenshot of how you are arriving on the result.

[萍]

模型和数据字典见附件