I've just started learning matlab and I am trying to solve this differential equation

I am new to MATLAB and I was trying to solve this differential equation and got the end result

syms y(x)
dy=diff(y);
ode= diff(y,x,2)+3*y==0;
cond1= y(0)==1;
cond2= dy(0)==0;
ysol(x)= dsolve(ode,cond1,cond2)

ysol(x) =

cos(3^(1/2)*x)

now if I want to solve y(1)=? in terms of y(1)=0.99 not cos(3^(1/2)) with 1 deg input argument. how should I do that? Thank you!

Answer 1

[Torsten]

Add the line

ysol(1)

at the end of your code.

[Ankit Gupta]

Sir! I did that but I want Answer as 0.99. It is showing cos(3^(1/2))

[Torsten]

cos(sqrt(3)) is not 0.99.

Or do you mean 1 deg instead of 1 rad as input argument ?

Use double(ysol(1)) or double(ysol(pi/180)) depending on whether you mean 1 rad or 1 deg.

[Ankit Gupta]

I beg your pardon, sir! I mean 1 deg input argument. Thank You sir!

Answer 2

[Dimitris Kalogiros]

you can access the value of y(1) by writting .... y(1)

syms y(x)

%dy=diff(y)

ode= diff(y,x,2)+3*y==0

cond1= y(0)==1
cond2= dy(0)==0

ysol(x)= dsolve(ode,cond1,cond2)

%--------------------------------
% just displaying value of y(1)

disp( ysol(1) )

[Ankit Gupta]

Sir! I did that but I want Answer as 0.99. It is showing cos(3^(1/2)) with i deg input argument.