how can we solve this 2 equation?

hi dear friends could you plz do me a favor and solve these two equations? the equations are for finding PV cost analysis.

i have two equations

b=53

n=20

1- A=(b+300)+250+100-400

2- P=(A*(1-(1+50)^-n)/50

b is variable b=1:5:50

the system is works for n=20 years. For every b variable i have to find P ;

thanks ;)

[KALYAN ACHARJYA]

Define all variables, after that just calculate ...

b=.................
n=.................
A=(b+300)+250+100-400; 
P=A*(1-(1+50)^-n)/50;

[Mamad Mamadi]

we have to use for loop i think coz b is variable i mean put 5xb to find p1 and put 10xb to find p2 and so on till 50xb

[Image Analyst]

Unless your teacher requires a loop, you don't need one. See Ameer's answer below.

Answer 1

[Ameer Hamza]

Both of the following codes are equivalent.

Vectorized:

n = 20;
b = 1:5:50;
A = (b+300)+250+100-400;
P = A*(1-(1+50)^-n)/50;

Result:

P =
  Columns 1 through 7
    5.0200    5.1200    5.2200    5.3200    5.4200    5.5200    5.6200
  Columns 8 through 10
    5.7200    5.8200    5.9200

For-loop

n = 20;
b = 1:5:50;
P = zeros(1,numel(b));
for i=1:numel(b)
    A = (b(i)+300)+250+100-400;
    P(i) = A*(1-(1+50)^-n)/50;
end

Result:

P =
  Columns 1 through 7
    5.0200    5.1200    5.2200    5.3200    5.4200    5.5200    5.6200
  Columns 8 through 10
    5.7200    5.8200    5.9200

[Image Analyst]

Can you format the code ONLY as Code, and not the command window stuff. Otherwise they can click Copy but get all the non-runnable stuff also. Then after they paste into a script, they'll have to delete the command window stuff or else get an error.

[Ameer Hamza]

Good idea. Thanks for pointing out.

[Mamad Mamadi]

Ameer Hamza thank you very much for your great answer realy helped me. but i wanna say the results are different from my calculation in excel am i wrong in calculation?

the results:

and how is it possible to show the results of A1 to A50 like P1 to P50 ?

[Ameer Hamza]

Mamad, in your question, the b was not multiplied with 83. If you multiply it, you will get the same answer

n = 20;
b = [1 5:5:50];
A = (83*b+300)+250+100-400;
P = A*(1-(1+50)^-n)/50;

[Mamad Mamadi]

ok understood your right thank you bro ☺

[Ameer Hamza]

I am glad to be of help.

[Mamad Mamadi]

Mr Ameer thanks for your helping, i wanted to mention that the codes you write give the wrong answer again coz i am new at matlab i didnt find the problem. i solved it in excel one by one but the answers are different?!! :( thanks

[Ameer Hamza]

Can you post the MATLAB code you are running?

[Mamad Mamadi]

i changed the values.

clc; clear all;
Cc= 1311.28          
M =  21              
R =  514             
S =  279          
I = 0.05                           
a=83    

n = 20;
b = 1:5:50;
P = zeros(1,numel(b));
for i=1:numel(b)
      A(i) = (a*b(i)+Cc+M+R)-S;
      P(i) = (A(i)*(1-(1+I)^-n))/I;
end      

[Ameer Hamza]

I am exactly getting the same values.

[Mamad Mamadi]

yes you are right sir but the problem is here coz when b=5 'A ' must be '1982' and P=24704 and so on.

[Ameer Hamza]

But column E of your excel sheet shows when b=5, then A=1650 and P=25737. The column H and I must have a different formula.

[Mamad Mamadi]

both of them are the same formula sir.

in matlabs answer, when b=5 then A=2065 and P=25737 give us the wrong answer.

but in excel sheet the answer is, when b=5 then A=1982 and P=24704

[Ameer Hamza]

Can you attach your excel file?

[Mamad Mamadi]

excel sheet

[Ameer Hamza]

Mamad, In this comment: https://www.mathworks.com/matlabcentral/answers/517357-how-can-we-solve-this-2-equation#comment_827851 I also modified the value of 'b'. But you didn't changed it in your code. Closely see the difference between the value of 'b', I wrote in that comment and your code, and you will find the mistake.