Cant figure out how to get my functions to graph

f=@(y) y.*(y-2).^2.*(y+4).^(3);
phaseLine(f,-6,4);

%% 5. 
y_min=-5; 
y_max=3;
f1=@(y) y.*(y.^2+4);
phaseLine(f1,y_min,y_max);

y_min=-5;
y_max=3;
f2=@(y) y.*(y.^2);
phaseLine(f2,y_min,y_max);

y_min=-5;
y_max=3;
f3=@(y) y.*(y.^2-1);
phaseLine(f3,y_min,y_max);

% Code Here



%%
% Comments: 

%% 6.
f=@(a,y) y.*(y.^2-a);
bifDiag244(f,-4,6,-6,6,1);


% Code Here

%%
% Comments:

%% 7.
f=@(a,y) y.*(y-a+1);
bifDiag244(f,-5,5,-6,6,1);
% Code Here

%%
% Comments: 

%% Functions 
function phaseLine(dydt4,y_min,y_max)
syms y
x=solve(dydt4(y)==0,y);
x=x(imag(x)==0);
hold on

for i=1:length(x)
    plot (0,x(i),".k")
end
if dydt4(x(1)-1)>0
    plot ([0,5],[y_min x(1)],'red')
else
    plot ([0,5],[y_min x(1)],'blue')
end
if dydt4(x(end)+1)>0
    plot([0,5], [y_max x(end)],'red')
else
    plot([0,5], [y_max x(end)],'blue')
end
for i=1:length(x)-1
    if dydt4((x(i)+x(i+1))/2>0)
        plot ([0,5],[x(i) x(i+1)],'red')
    else
        plot ([0,5], [x(i) x(i+1)],'blue')
    end
end
end

[Rik]

This time I edited your question for you. Next time, please use the tools explained on this page to make your question more readable.

Answer 1

[Walter Roberson]

f=@(y) y.*(y-2).^2.*(y+4).^(3);
phaseLine(f,-6,4);

%% 5. 
y_min=-5; 
y_max=3;
f1=@(y) y.*(y.^2+4);
phaseLine(f1,y_min,y_max);

y_min=-5;
y_max=3;
f2=@(y) y.*(y.^2);
phaseLine(f2,y_min,y_max);

y_min=-5;
y_max=3;
f3=@(y) y.*(y.^2-1);
phaseLine(f3,y_min,y_max);

% Code Here



%%
% Comments: 

%% 6.
f=@(a,y) y.*(y.^2-a);
bifDiag244(f,-4,6,-6,6,1);

Unrecognized function or variable 'bifDiag244'.

% Code Here

%%
% Comments:

%% 7.
f=@(a,y) y.*(y-a+1);
bifDiag244(f,-5,5,-6,6,1);
% Code Here

%%
% Comments: 

%% Functions 
function phaseLine(dydt4,y_min,y_max)
syms y
x=solve(dydt4(y)==0,y);
x=x(imag(x)==0);
hold on

for i=1:length(x)
    plot (0,x(i),".k")
end
if dydt4(x(1)-1)>0
    plot ([0,5],[y_min x(1)],'red')
else
    plot ([0,5],[y_min x(1)],'blue')
end
if dydt4(x(end)+1)>0
    plot([0,5], [y_max x(end)],'red')
else
    plot([0,5], [y_max x(end)],'blue')
end
for i=1:length(x)-1
    if dydt4((x(i)+x(i+1))/2)>0              %FIXED
        plot ([0,5],[x(i) x(i+1)],'red')
    else
        plot ([0,5], [x(i) x(i+1)],'blue')
    end
end
end