MATLAB: Question on Graphing / Plotting

matlab function

Currently i have:

 syms x
Y = sqrt ((x^4 - x + 1) / x^4 + x +1 )

I take the derivative of that using diff Y and get one.

The problem I am having is trying to graph the original Y and the diff Y on the same screen. It wont allow me to plot either through the workspace and was wondering if theres a simple command to use to graph them for comparison. Any help would be appreciated thank you!

Best Answer

You're likely looking for ezplot. Regular plot doesn't play well with syms:

syms x
Y = sin(x);
dY = diff(Y);
ezplot(Y,dY);

Related Solutions

MATLAB: How to define a function

Take the derivative as a symbolic object, not a function handle:

syms y(t)
Dy = diff(y,t); D2y = diff(y,t,t);
DE = D2y + 4*Dy + 4*y == 0
y = dsolve(DE, y(0)==1, Dy(0)==2)
Y = matlabFunction(y)
DY = diff(y)

You can then use matlabFunction to create an anonymous function from ‘DY’.

EDIT —

This code:

syms y(t)
Dy = diff(y,t); D2y = diff(y,t,t);
DE = D2y + 4*Dy + 4*y == 0;
y = dsolve(DE, y(0)==1, Dy(0)==2);
Y_fcn = matlabFunction(y)
DY = diff(y);
DY_fcn = matlabFunction(DY)

produces these anonymous functions:

Y_fcn = @(t)exp(t.*-2.0)+t.*exp(t.*-2.0).*4.0
DY_fcn = @(t)exp(t.*-2.0).*2.0-t.*exp(t.*-2.0).*8.0;

MATLAB: Plot the exp function

syms y(t)
eq=diff(y,2)+13*diff(y)+40*y==4;
Dy=diff(y);
Y(t)=dsolve(eq,[y(0)==0 Dy(0)==0])
t=0:0.001:0.9;
plot(t,Y(t))

Best Answer

Related Solutions

MATLAB: How to define a function

MATLAB: Plot the exp function

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