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[b][code]>> help sym
sym Construct symbolic numbers, variables and objects.
S = sym(A) constructs an object S, of class 'sym', from A.
If the input argument is a string, the result is a symbolic number
or variable. If the input argument is a numeric scalar or matrix,
the result is a symbolic representation of the given numeric values.
If the input is a function handle the result is the symbolic form
of the body of the function handle.
x = sym('x') creates the symbolic variable with name 'x' and stores the
result in x. x = sym('x','real') also assumes that x is real, so that
conj(x) is equal to x. alpha = sym('alpha') and r = sym('Rho','real')
are other examples. Similarly, k = sym('k','positive') makes k a
positive (real) variable. x = sym('x','clear') restores x to a
formal variable with no additional properties (i.e., insures that x
is NEITHER real NOR positive). Defining the symbol 'i' will use
sqrt(-1) in place of the imaginary i until 'clear' is used.
See also: SYMS.
A = sym('A',[M N]) creates M-by-N vectors or matrices of symbolic scalar
variables. Elements of vectors have names of the form Ak and elements
of matrices have names of the form Ai_j where k,i or j range over 1:M
or 1:N. The form can be controlled exactly by using '%d' in the first
input (eg 'A%d%d' will make names Aij).
A = sym('A',N) creates an N-by-N matrix.
sym(A,ASSUMPTION) makes or clears assumptions on A as described in
the previous paragraph.
Statements like pi = sym('pi') and delta = sym('1/10') create symbolic
numbers which avoid the floating point approximations inherent in the
values of pi a