Subscript indices must either be real positive integers or logicals with minimum and maximum values

I am trying to obtain the max and min. values from the following arrays:, however, I got the above mentioned error, any help

clear all; 
clc;
syms y real;

y2min=double(solve(-246<.7500*-50+(y*.2500)+20.78,y));
y2max=double(solve(.7500*-50+(y*.2500)+20.78<40,y));

y3min=double(solve(-68<-.433*-50+(y*.4330)+20.78,y));
y3max=double(solve(-.433*-50+(y*.4330)+20.78<68,y));
min(:)=[y1min y2min y3min]
max(:)=[y1max y2max y3max]

min_n=max(min)

max_n=min(max(:))

Answer 1

[KALYAN ACHARJYA]

Change the variable name min and max to different one say min1 or max1

min(:)=[y1min y2min y3min]
max(:)=[y1max y2max y3max]