线性规划问题MATLAB报错

问题遇到的现象和发生背景

MATLAB报错，线性规划问题

问题相关代码，请勿粘贴截图

clc,clear
a = [0.5 0.25 0.1;0.4 0.4 0.15];
b = [600,750,625];
pa = [24,15];
pb = [20,12,8];
prob = optimproblem("ObjectiveSense",'max'); %创建优化问题
x = optimvar('x',2,3,'LowerBound',0); %创建优化变量
inc = pa * sum(x,2); %计算收入
cos = sum(x) * pb'; %计算成本
prob.Objective = inc - cos; %目标函数
rat = a ./ repmat(sum(x,2),1,3);
ano = [1,1,-1;-1,-1,1];
prob.Constraints.con1 = rat .* ano >= a .* ano;
prob.Constraints.con2 = sum(x) <= b;
prob.Constraints.con3 = sum(x,2) >= [600;800];%约束条件
[sol,favl] = solve(prob);
sol.x

运行结果及报错内容

Solving problem using fmincon.
错误使用 optim.problemdef.OptimizationProblem/solve
SOLVE requires a non-empty initial point structure to solve a nonlinear problem.

出错 untitled (第 16 行)
[sol,favl] = solve(prob);

你的Matlab版本的多少呢，matlab 2019 中已经不接受向 solve 中传入字符串