MATLAB Answers

Nawal
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How to assign a value of differential equation?

Asked by Nawal
on 29 Jul 2013
Not sure how to ask my question, but for example if I have
a= sin(5)+3x
I want to assign its differential value to b, how can I write this?
I can do: diff a
now how to make the answer equal to b b =

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1 Answer

Answer by David Sanchez
on 29 Jul 2013

Derivatives: Using MATLAB
Using symbolic computation you can obtain analytical derivatives in MATLAB The function is diff(..)
% analytical derivatives
syms x y
y= sin(x); dy = diff(y,'x')
y=exp(2*x); dy = diff(y)
% derivative with respect to x is understood
f = sin(x); g = 2*x^2+3*x + 1;
y = f*g
dy =diff(y) % derivative of product
u= 2*x + 3; f = sin(u);
diff(f) % chain rule
Output from MATLAB
dy =
cos(x)
dy =
2*exp(2*x)
y =
sin(x)*(2*x^2+3*x+1)
dy =
cos(x)*(2*x^2+3*x+1)+sin(x)*(4*x+3)
ans =
2*cos(2*x+3)

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