# adding for loop with linspace with many variables

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dana akil on 24 Jul 2022
Commented: dana akil on 24 Jul 2022
Hi ,
I am trying to run this script but keep having errors ,please help
wg=0.18;
ws=0.12;
a=0.425;
b=2.353;
c=0.06;
d=0.18;
e=0.12;
p1 = 0.015604;
p2 = -1.4201;
p3 = 53.8951;
p4 = -1091.1818;
p5 = 12425.3578;
p6 = -75422.3333;
p7 = 190602.4449;
qp1 = 1.1584;
qp2 = -110.2867;
qp3 = 4362.3758;
qp4 = -91752.2953;
qp5 = 1082176.2735;
qp6 = -6786040.7706;
qp7 = 17674223.7811;
%x= linspace(10,30,20); %pitta
r= sqrt(410-(x.^2));
rr= (r).^2;
y1= @(x) (r.*wg);
%A = @(x) p1*x.^6 + p2*x.^5 + p3*x.^4 + p4*x.^3 + p5*x.^2 + p6.*x + p7 ;
%B= @(x) qp1*x.^6 + qp2*x.^5 +qp3*x.^4 + qp4*x.^3 +qp5*x.^2 + qp6.*x + qp7;
R = sqrt(235.72-rr);
T= @(x) 2.353*(R./r);
x= linspace(10,30,20);
for i=10:20r(i)
r(i)= sqrt(410-(i.^2));
rr(i)= (r(i)).^2;
A(i) = p1*i.^6 + p2*i.^5 + p3*i.^4 + p4*i.^3 + p5*i.^2 + p6.*i + p7 ;
B(i)= qp1*i.^6 + qp2*i.^5 +qp3*i.^4 + qp4*i.^3 +qp5*i.^2 + qp6.*i + qp7;
R(i) = sqrt(235.72-rr(i));
T(i)= 2.353*(R(i)./r(i));
yup(i) = A5(x).*T(x)+B5(x);
end
ydown=@(x) A5-B5.*T;
y2= yup./ydown;
y3= atan(y2)+2*pi;
plot (x,y1(x))
hold on
plot (x,A(x))
plot (x,B(x))
dana akil on 24 Jul 2022
I just need it to calculate all the variables one by one
for i=10
r(10) is
rr(10 ) is then calculate A(10 )
it keeps giving me one value

Alberto Cuadra Lara on 24 Jul 2022
Edited: Alberto Cuadra Lara on 24 Jul 2022
Hello Dana,
There are inconsistencies in your code:
• x is not defined before use it
• The loop is not properly defined, for i = 10 : 20 * r(i) ??
• I do not see why you need to use a for loop here. MATLAB works great using vectorization.
• A5 and B5 are not defined.
Please, clarify these points.
Best,
Alberto
##### 1 CommentShowHide None
dana akil on 24 Jul 2022
I removed the for loop and it works fine
Thank you
But I have adiffrent proplem now
Array indices must be positive integers or logical values.
at y2 line
wg=0.18;
ws=0.12;
a=0.425;
b=2.353;
c=0.06;
d=0.18;
e=0.12;
p1 = 0.015604;
p2 = -1.4201;
p3 = 53.8951;
p4 = -1091.1818;
p5 = 12425.3578;
p6 = -75422.3333;
p7 = 190602.4449;
qp1 = 1.1584;
qp2 = -110.2867;
qp3 = 4362.3758;
qp4 = -91752.2953;
qp5 = 1082176.2735;
qp6 = -6786040.7706;
qp7 = 17674223.7811;
%x= linspace(10,30,20); %pitta
r= sqrt(410-(x.^2));
rr= (r).^2;
y1= @(x) (r.*wg);
A = @(x) p1*x.^6 + p2*x.^5 + p3*x.^4 + p4*x.^3 + p5*x.^2 + p6.*x + p7 ;
B= @(x) qp1*x.^6 + qp2*x.^5 +qp3*x.^4 + qp4*x.^3 +qp5*x.^2 + qp6.*x + qp7;
R = sqrt(235.72-rr);
T= 2.353*(R/r);
x= linspace(10,30,20);
r= sqrt(410-(x.^2));
rr = (r).^2;
yup = @(x) A(x)*T+B(x);
ydown=@(x) A(x)-B(x)*T;
figure(1)
%plot(x , yup(x))
%hold on
%plot(x , ydown(x))
y2(x)= real(yup(x)/ydown(x));
y3(x)= real(atan(y2)+2*pi);
figure(2)
plot (x,y3(x))
plot (x,y1(x))
hold on

Alberto Cuadra Lara on 24 Jul 2022
Edited: Alberto Cuadra Lara on 24 Jul 2022
Hi Dana,
I'm not sure if this is what you expect, but here is the code without errors. I have changed the handle functions to vectors.
% Constants
wg = 0.18;
ws = 0.12;
a = 0.425;
b = 2.353;
c = 0.06;
d = 0.18;
e = 0.12;
p1 = 0.015604;
p2 = -1.4201;
p3 = 53.8951;
p4 = -1091.1818;
p5 = 12425.3578;
p6 = -75422.3333;
p7 = 190602.4449;
qp1 = 1.1584;
qp2 = -110.2867;
qp3 = 4362.3758;
qp4 = -91752.2953;
qp5 = 1082176.2735;
qp6 = -6786040.7706;
qp7 = 17674223.7811;
% Definitions
x = linspace(10, 30, 20);
% Calculations
r = sqrt(410 - (x.^2));
rr = r.^2;
A = p1*x.^6 + p2*x.^5 + p3*x.^4 + p4*x.^3 + p5*x.^2 + p6.*x + p7 ;
B = qp1*x.^6 + qp2*x.^5 + qp3*x.^4 + qp4*x.^3 + qp5*x.^2 + qp6.*x + qp7;
R = sqrt(235.72 - rr);
T = 2.353*(R ./ r);
yup = A .* T + B;
ydown = A - T .* B;
y1 = real(r * wg);
y2 = real(yup ./ ydown);
y3 = real(atan(y2) + 2*pi);
% Plot figure
figure;
hold on;
plot (x, y3)
plot (x, y1)
##### 1 CommentShowHide None
dana akil on 24 Jul 2022
Thank you
many thanks