Unable to called a function

I have an Integrators and Deriivatives function, which when I called the integrators, it would said "Unrecognized function or variable 'rk78_mex'.". I have ran this program before but for some reason it is not working now.

[Cris LaPierre]

Where is the function rk78_mex located?

• a local function - check your spelling
• a function file - is it in your current folder? If not, is it in a folder that has been added to your MATLAB path?

[kim]

The function rk78_mex, is a c file which I am calling to intergrated kinda like ode45. the integrator is apart of another folder which is in my documents which is on my path. it part of a github, my groups has.

Answer 1

[Walter Roberson]

You are using a third-party package that implements some of its functionality through mex code. The package is calling upon rk78_mex . However, the system is unable to find a dll named rk78_mex .

You may need to use the mex command to regenerate rk78_mex

Answer 2

[Steven Lord]

If you're using release R2021b or later, consider using the ode78 function that is part of MATLAB as of that release.

If that is not an option, does the folder containing the rk78_mex MEX file contain an rk78_mex file that has the appropriate extension (as listed by mexext) for your computer's architecture? Often when a MEX-file is not found when a user expects it to be available (perhaps because it works on a colleague's machine) it is because it has not been built for their computer's architecture. A Windows MEX-file (with extension .mexw64) won't run on a Linux machine (which would require a MEX-file compiled for Linux, with the extension .mexa64.)

struct2table(mexext('all'))

ans = 4x2 table
         ext            arch    
    _____________    ___________

    {'mexa64'   }    {'glnxa64'}
    {'mexmaca64'}    {'maca64' }
    {'mexmaci64'}    {'maci64' }
    {'mexw64'   }    {'win64'  }

I've seen this commonly in the past few years with older MEX-files that the authors have not built on Apple Silicon.