calling a matlab function with scalar type

2 次查看（过去 30 天）

Richard Poley 2017-1-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/322565-calling-a-matlab-function-with-scalar-type

评论： Richard Poley 2017-1-30

I am collecting data from a Simulink model into an array so I can manipulate it using a custom function in Matlab. The data is an array of dimensions 1601 x 1, single precision data. Now, I want to operate on one element of this data with my own function which is written in C and converted into a MEX function.

The function works fine with data entered like this:

x = 0.2345
myFunc(x)

...yet when I do this:

x = arr(100)
myFunc(x)

I get the error:

Error using myFunc
Input multiplier must be a scalar.

...however this

isscalar(x)

...yields this...

ans =
  logical
  1

...so is 'x' a scalar or not?

If not, how can I make it a scalar so I can call it with my function? Thanks.

6 个评论
显示 4更早的评论隐藏 4更早的评论

Geoff Hayes 2017-1-30

Richard - can you attach the C code instead? I would like to see that as opposed to the compiled Mex function. (Should be able to just attach the code rather than a zip file, even if you have to rename it with a txt extension.)

Richard Poley 2017-1-30

Sorry, Geoff. It's proprietary so I'll need to check.

I'll post back when I know.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Geoff Hayes 2017-1-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/322565-calling-a-matlab-function-with-scalar-type#answer_252658

在 MATLAB Online 中打开

No worries, Richard. One other thing you may want to consider trying is to cast your x to a double. The example

 x = 0.2345
 class(x)

shows the x is a double and since this works (as expected) then you may want to try that for the other. For example,

 x = double(arr(100));
 myFunc(x)

Now, you will be passing in the same data type. The error message might be misleading and so we see Input multiplier must be a scalar rather than the "true" error message which might be "Input multiplier must be a double rather than a single". This is just a guess though! :)