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## Help Plotting Symbolic Vector Fields with Substitutions

 From: WARDEVIL_UFO Subject: Help Plotting Symbolic Vector Fields with Substitutions Date: Mon, 17 Apr 2017 16:13:04 -0700 (PDT)

https://www.mathworks.com/help/symbolic/create-plots.html
<http://https://www.mathworks.com/help/symbolic/create-plots.html>

I am attempting a quiver plot of symbolic functions starting with the
following example from MatLab.  It appears the substitution gets hung up
some reason.

syms x y
u = sin(x^2 + y^2);
v = cos(x*y);
[X, Y] = meshgrid(-1:.1:1,-1:.1:1);
U = subs(u, [x y], {X,Y});
V = subs(v, [x y], {X,Y});
quiver(X, Y, U, V)

I get the following error messages:
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: called from
sym at line 221 column 7
numeric_array_to_sym at line 36 column 14
sym at line 199 column 7
cell_array_to_sym at line 16 column 11
sym at line 195 column 7
subs at line 126 column 7
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)
warning: Using rat() heuristics for double-precision input (is this what you
wanted?)

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