adjmat unrecognized function in Matlab

I'm trying to run a code and it has the function

t5 = diff(lambda);
t5 = adjmat(t5);

but I got the error that adjmat unrecognized function , so what is the problem?

[Walter Roberson]

What is class(lambda) ? And what do you expect adjmat() to caclulate?

[Walter Roberson]

Seems to be from a published suite by CRC press that appears in multiple textbooks, with relevant function names such as totdisp_SMF.m

However I cannot find any adjmat() function that seems likely to be relevant.

[Diana]

Yes, this code is froma textbook for optical communication

[Walter Roberson]

What is it expected that the function will do?

If you match the code to the theory, what role is adjmat() playing there?

[Diana]

The theory is the part of the differential, but the adjmat is not related to theory

[Walter Roberson]

At the top of your function put in

adjmat = @(M) mat2gray(M);

Answer 1

[Matt J]

Is adjmat supposed to be computing the adjugate of the matrix t5. If so, you might be able to use this instead,

https://www.mathworks.com/matlabcentral/fileexchange/12692-adjugate-adjoint-of-a-square-matrix

Answer 2

[Jian Yuan]

After diff function, the dimention of an array decreased by 1. I checked here Adjmat(t5) seems to align that. So you may try t5(:,1) = [] to replace t5 = adjmat(t5).