When did the syntax for linprog change

At one point, the input syntax for linprog was

x=linprog(f,A,b,Aeq,beq,lb,ub,x0,options)

but now (R2023b) I see that it has changed to,

x = linprog(f,A,b,Aeq,beq,lb,ub,options)

In what release was the support for the first syntax discontinued?

[Walter Roberson]

Before R2019a -- at least the x0 is not documented in R2019a.

Answer 1

[Naga]

Hello Matt,

I had the same question and was trying to achieve the same functionality. After some investigation, I discovered that the support for the initial point x0 in the linprog function was removed starting with MATLAB R2023a.

[Matt J]

Can you say how you discovered this? As @Walter Roberson says, the online documentation says it has been gone since R2019.

[Naga]

I tried to use the command in MATLAB R2022b and it was working fine and when I used the same command in MATLAB R2023a it was throwing an error.

[Matt J]

Were you actually using the intial point x0? By 2022b, the only linear programming algorithms available were interior-point, interior-point-legacy, and dual-simplex, neither of which make use of an initial point.

[Matt J]

I just got confirmation from Tech Support that " the "x0" input to "linprog" was removed in R2023a."

Thanks a lot.

Answer 2

[Walter Roberson]

R2018b documents

X = linprog(f,A,b,Aeq,beq,LB,UB,X0) sets the starting point to X0. This

option is only available with the active-set algorithm. The default

interior point algorithm will ignore any non-empty starting point.

As of R2019a, active-set is not a recognized algorithm