Error : Constant Operands

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Life is Wonderful 2022-3-23

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1678724-error-constant-operands

编辑： Life is Wonderful 2022-3-31

采纳的回答： David Hill

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Hi

Iam implementing following code as show below

m = 10;
v = [1 1 2 : m]
v = 1×11
     1     1     2     3     4     5     6     7     8     9    10

If I try to make fixed point , I am getting the error "Operands must be constants." I don't understand what is expected here. Can someone help me ?

Thank you

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Geoff Hayes 2022-3-23

@Jogger - please clarify what you mean by "try to make this fixed point". What line of code leads to the error message?

Life is Wonderful 2022-3-25

try to make this fixed point - Sorry I didn't write my requirment clearly.

I mean m is a Embedded.fi object here . Let say m = 10 , then class of m is 'double' but when I use numerictype or fi, then m is translated to 'embedded.fi'.

The problem i see colon operator doesn't seems to work for 'embedded.fi'.

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Answer 1

David Hill 2022-3-25

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Does changing to double work? I don't have the toolbox

v = [1 1 2 : double(m)]

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Life is Wonderful 2022-3-28

Thanks a lot, it works

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Answer 2

Andy Bartlett 2022-3-29

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I'm puzzled by the error you described "Operands must be constants.".

When I attempt to reproduce the issue, I don't observe any problem.

I created this simple function.

function y = makeVec(m)
    y = [1 1 2 : m];
end

When I test this with double or fixed-point inputs

u1 = 10;
u2 = fi(10);
y1 = makeVec(u1)
y2 = makeVec(u2)

the outputs are as expected.

y1 =
     1     1     2     3     4     5     6     7     8     9    10
y2 = 
     1     1     2     3     4     5     6     7     8     9    10
          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 16
        FractionLength: 0

Code generation can provide additional restrictions, so I tried that too.

codegen makeVec -args {u1} -o makeVec1_mex
codegen makeVec -args {u2} -o makeVec2_mex
y1m = makeVec1_mex(u1)
y2m = makeVec2_mex(u2)

Again, the outputs were as expected.

y1m =
     1     1     2     3     4     5     6     7     8     9    10
y2m = 
     1     1     2     3     4     5     6     7     8     9    10
          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 16
        FractionLength: 0

If you could clarify the original reproduction steps, that would be appreciated.

Andy

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Life is Wonderful 2022-3-29

编辑：Life is Wonderful 2022-3-31

Thanks @Andy Bartlett,

The problem i see is coming from factorial function in matlab . Factorial function is unsupport by the fixed point designer . So I wrote my own implementation. I reliased the mistake in declaring fi Object and double togeather.

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