Edição das 17h18min de 27 de setembro de 2016

Funções importantes para o uso do cálculo simbólico

vpa(x) Variable-precision arithmetic: evaluate each element of the symbolic input x to at least d significant digits, where d is the value of the digits function. The default value of digits is 32.
digits(d) Change variable precision used: sets the precision used by vpa to d significant decimal digits. The default is 32 digits.
double(s) Convert symbolic values to MATLAB double precision: converts the symbolic value s to double precision. Converting symbolic values to double precision is useful when a MATLAB® function does not accept symbolic values.
x = sym('x') creates symbolic variable x
syms x Create symbolic variables and functions: Create symbolic variable x.
p = poly2sym(c) Create symbolic polynomial from vector of coefficients: creates the symbolic polynomial expression p from the vector of coefficients c.
S = solve(eqn,var) Equations and systems solver.
subs(s,new) Symbolic substitution.
g = matlabFunction(f) Convert symbolic expression to function handle or file.
simplify(S) Algebraic simplification
expand(S) Symbolic expansion of polynomials and elementary functions
F = factor(x) Factorization
numden(A) Extract numerator and denominator
partfrac(expr,var) Partial fraction decomposition
latex(S) LaTeX form of symbolic expression

syms x y
f = sin(x)^2 + cos(y)^2;
diff(f)

ans =
2*cos(x)*sin(x)

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 *[http://www.mathworks.com/help/symbolic/sym.html x = sym('x')] creates symbolic variable x
 *[http://www.mathworks.com/help/symbolic/syms.html syms x] Create symbolic variables and functions: Create symbolic variable x.
-*[http://www.mathworks.com/help/symbolic/solve.html S = solve(eqn,var)] Equations and systems solver:
+*[http://www.mathworks.com/help/symbolic/poly2sym.html p = poly2sym(c)] Create symbolic polynomial from vector of coefficients: creates the symbolic polynomial expression p from the vector of coefficients c.
+*[http://www.mathworks.com/help/symbolic/solve.html S = solve(eqn,var)] Equations and systems solver.
+*[http://www.mathworks.com/help/symbolic/subs.html subs(s,new)] Symbolic substitution.
 *[http://www.mathworks.com/help/symbolic/matlabfunction.html g = matlabFunction(f)] Convert symbolic expression to function handle or file.
 *[https://www.mathworks.com/help/symbolic/simplify.html simplify(S)] Algebraic simplification