please help me plotting the curve. Its working fine till second last line but not plotting the curve.

syms x A

theta=[0:10:360]

n=4.25

val1=3.271 %value of 6nU

val2=12.45481 %value of 12nw J=(0.2728*(x.^3)-0.0592*x)*(10.^(-3))*0.055*(sind(theta)+(sind(2*theta)./(2*((18.0625-((sind(theta)).^2)).^(1/2)))))

G=val1*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-2))

H=val2*J*int(x*((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3)))

K=A*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3))

y=0.055*((1-cosd(theta))+(n-sqrt(square(n)-(sind(theta)).^2)))

P=G+H+K

P=double(subs(P,(x),(y)))

fplot(theta,P)

Answer 1

[Star Strider]

You have not defined ‘A’, so it is not possible to evaluate ‘P’ in order to plot it.

Changing your code slightly:

syms x A
theta=0:10:360;
n=4.25;
val1=3.271; %value of 6nU
val2=12.45481; %value of 12nw
J=(0.2728*(x.^3)-0.0592*x)*(10.^(-3))*0.055*(sind(theta)+(sind(2*theta)./(2*((18.0625-((sind(theta)).^2)).^(1/2)))));
G=val1*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-2));
H=val2*J*int(x*((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3)));
K=A*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3));
y=0.055*((1-cosd(theta))+(n-sqrt(square(n)-(sind(theta)).^2)));
P=G+H+K;
PF= matlabFunction(P)
fplot(PF, [0 360])

produces:

PF =

    function_handle with value:

      @(A,x)[(x.*6.424017204651876+x.^3.*2.354624018983744)./(x.^2.*(-4.326979472140762)+ ...

The function is too long to display in the Command Window.

Provide a value for ‘A’, and your code could work.

[Star Strider]

This version works:

syms x 
A=1.5;
theta= sym(0:10:360);
n=4.25;
val1=3.271; %value of 6nU
val2=12.45481; %value of 12nw
J=(0.2728*(x.^3)-0.0592*x)*(10.^(-3))*0.055*(sind(theta)+(sind(2*theta)./(2*((18.0625-((sind(theta)).^2)).^(1/2)))));
G=val1*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-2));
H=val2*J*int(x*((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3)));
K=A*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3));
y=0.055*((1-cosd(theta))+(n-sqrt(square(n)-(sind(theta)).^2)));
P=G+H+K;
P=subs(P,x,y);
Pv = double(P);
Tv = linspace(0, 360, numel(Pv));

plot(Tv, Pv)
grid

After a few minutes, it produces a rather ordinary-appearing sine function plot.

[Shalabh Singhal]

Undefined function 'sind' for input arguments of type 'sym'.

Error in Untitled (line 7)

J=(0.2728*(x.^3)-0.0592*x)*(10.^(-3))*0.055*(sind(theta)+(sind(2*theta)./(2*((18.0625-((sind(theta)).^2)).^(1/2)))));

>> This is the error being shown by the command window of matlab 2016a

[Star Strider]

That is correct. The degree-argument trigonometric functions are not defined in the Symbolic Math Toolbox. I am using R2018a, that did not throw that error.

Replace:

sind(theta)

with:

sin(theta*pi/180)

and the error should not appear.

Answer 2

[Shalabh Singhal]

sorry but still not working. Take A=1.5

Answer 3

[Shalabh Singhal]

sir, this is my final code.There is till some issue.I forgot to add 'subs' earlier. syms x

theta=0:10:360;

n=4.25;

val1=3.271; %value of 6nU

val2=12.45481; %value of 12nw

J=(0.2728*(x.^3)-0.0592*x)*(10.^(-3))*0.055*(sind(theta)+(sind(2*theta)./(2*((18.0625-((sind(theta)).^2)).^(1/2)))));

G=val1*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-2));

H=val2*J*int(x*((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3)));

K=2*int((0.0682*(x.^4)-0.2951*(x.^2)+1.041).^(-3));

y=0.055*((1-cosd(theta))+(n-sqrt(square(n)-(sind(theta)).^2)));

P=G+H+K;

P=subs(P,(x),(y));

PF= matlabFunction(P)

fplot(PF, [0 360])