plot function f(x)

Referring to figure below, plot the function f(x) in the domain −2 ≤ x ≤ 5 using Method 1 and Method 2.

a) Method 1: write a program in a script file using conditional statements and loops

b) Method 2: create a user-defined function for f(x) and then use the function in a script file to make the plot.

[darova]

Can you please show something? Do you have any ideas?

[xavier]

method 1

x=[-2:5];
n=input('Enter the n value');
for k=1:n
    S(k)=(-1)^k*k/2^k;
if x<=-1
    y=20;
elseif x<=-1 & x<=1
    y=(-5*x)+5;
elseif x<=1 & x<=3
    y=(-10*x.^2)+(35*x)-21
elseif x<=3 & x<=4
    y=(-5*x)+11;
elseif x>=4
    y=-10;
end
end

[xavier]

for the method 2

%PLOTTING MULTIPLE GRAPHS IN THE SAME PLOT Using 
x=[-2:5];
y=20;
yd=-5*x+5;
ydd=(-10*x.^2)+35*x-21;
yddd=(-5*x)+11;
ydddd=-10;
plot(x,y,'--b',x,yd,'-c',x,ydd,'--y',x,yddd,'-g',x,ydddd,'--k')

Answer 1

[darova]

Here are some suggestions for method 1

[xavier]

it is like this ? then what value must i key in ?

[darova]

You made some mistakes, look

[xavier]

so what should i write at the command window

[Walter Roberson]

your else are wrong. not x(k)<=-1 and instead x(k)>-1

[xavier]

sorry for asking walter, may i know which row do you refer ?

it is like this walter ?

[darova]

YOu can simply your if...else conditions

x = -2:0.1:5;       % note the dot '0.1', not '0,2'
for k = 1:length(x)
    if x(k) < -1
        % condition 1
    elseif x(k) < 1
        % condition 2
    elseif x(k) < 3
        % condition 3
    elseif x(k) < 4
        % condition 4
    else
        % condition 5
    end
end
plot(x,y)

Answer 2

[Sasika]

f(x)=x^2+5*x-6 -8<x<3

[Walter Roberson]

That code will fail for non-scalar x, or for x numeric that is not either positive integer or else logical true or false. And it likely gives u desirable answers in most cases.

Please do some testing of your code before posting your solutions as Answer to a Question.