       PDE Notation options (one works the other does not)

• To: mathgroup at smc.vnet.net
• Subject: [mg51336] PDE Notation options (one works the other does not)
• From: "Prince-Wright, Robert G SEPCO" <robert.prince-wright at shell.com>
• Date: Thu, 14 Oct 2004 06:37:45 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Hello Group.

Can someone explain why 'format 1' below works but 'format 2' does not.
Also how do you know when to use the different Notations for partial
derivatives.

thanks
Bob

===== format 1

\!\(\*
RowBox[{"solution", "=",
RowBox[{"u", "/.",
RowBox[{"First", "[", "\[IndentingNewLine]",
RowBox[{"NDSolve", "[", "\[IndentingNewLine]",
RowBox[{
RowBox[{"{", "\[IndentingNewLine]",

RowBox[{\(?\_t u[x, t] == \(-0.1\)\ \
u[x, t] - 2\ ?\_x u[x, t] + \ 0.3\ \ ?\_{x, 2}u[x, t]\), ",",
"\[IndentingNewLine]", \(u[x, 0] == 0\), ",",
"\[IndentingNewLine]", \(u[0,
t] == 5\ \((1 - Exp[\(-t\)])\)\), ",", =
"\[IndentingNewLine]",
RowBox[{
RowBox[{
SuperscriptBox["u",
TagBox[\((1, 0)\),
Derivative],

MultilineFunction->None], "[", \(20, t\),
\
"]"}], "==", "0"}]}], "\[IndentingNewLine]", "}"}], ",",
"\[IndentingNewLine]", "u", ",", \({x, 0, 20}\), ",",
\({
t, 0, 10}\)}], "]"}], "]"}]}]}]\)

===== format 2

\!\(solution = u /.
First[\[IndentingNewLine]NDSolve[\[IndentingNewLine]{\
\[IndentingNewLine]?\_t u[x, t] == \(-0.1\)\ \ u[x, t] - 2\ ?\_x
u[x,
t] + \ 0.3\ \ ?\_{x, 2}u[x,
t], \[IndentingNewLine]u[x, 0] ==
0, \[IndentingNewLine]u[0, t] == 5\ \((1 -
Exp[\(-
t\)])\), \[IndentingNewLine]?\_x\ u[20, t] ==
0\[IndentingNewLine]}, \[IndentingNewLine]u, {x, 0,
20}, {t,
0, 10}]]\)

Robert Prince-Wright
Risk Management Engineer, EP Americas
Shell Exploration & Production Company
One Shell Square
P. O. Box 61933
New Orleans
LA 70161-1933
United States of America

Tel: +1 504 728 7720
Fax: +1 504 728 4573
Email: robert.prince-wright at shell.com
Internet: http://www.shell.com

```

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