I find d from 7*d mod 40=1

I find d from 7*d mod 40 =1

 syms d
 eqn= 7*d==1;
solve(eqn,d,Domain=Dom::IntegerMod(40))

But there error. Help me please.

[Geoff Hayes]

Sakunrat - please describe the error. Include the full text.

[Walter Roberson]

What is the error message?

[Sakunrat Jaejaima]

I tried the codes but thereis no error shown. Matlab instead asked for/tried to open some matlab files

Answer 1

[Walter Roberson]

Try

feval(symengine, 'solve', eqn, d, sym('Domain=Dom::IntegerMod(40)'))

Domains are MuPAD objects, and you need to call into MuPAD to use them.

[Sakunrat Jaejaima]

Thank you so mush .