# [Maxima] Solve for [lhs(diff(%,x), rhs(diff(%,x)]

William Porter wmporter.omegapar at comcast.net
Sat Aug 7 18:16:41 CDT 2010

```Barton thank you,

I did solve my problem with your help and I thank you for your support into
looking at this issue. My solution is...

(%i1) x^2+d*y*4+d^2*(-4)\$
(%i2) e1:  rhs(first(solve(x^2+d*y*4+d^2*(-4),y)));
2      2
x  - 4 d
(%o2)                             - ---------
4 d
(%i3) e2: subst([x=50, d=25],[first(diff(e1,x)), diff(e1,x)]);
(%o3)                              [1, - 1]
(%i4) %phi[1] : first(e2);
(%o4)                                  1
(%i5) %phi[2] : second(e2);
(%o5)                                 - 1
(%i6)

William Porter
wporter at omegapar.com

-----Original Message-----
From: Barton Willis [mailto:willisb at unk.edu]
Sent: Saturday, August 07, 2010 12:11 PM
To: William Porter
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] Solve for [lhs(diff(%,x), rhs(diff(%,x)]

(%i1) rhs(first(solve(x^2+d*y*4+d^2*(-4),y)))\$
(%i2) [%,subst(x=-x,diff(%,x)), diff(%,x)]\$

Define a function larry that returns a list [y(x,d), dy/dx (-x,d),
dy/dx(x,d)]

(%i3) larry(x,d) := ''%\$

Check one value

(%i4) larry(10,5);
(%o4) [0,1,-1]

Generate a table (matrix) of values:

(%i5) funmake('matrix, map(lambda([x], append(x, float(apply(larry,x)))),
[[10,5], [10,10],[50,25], [50,50],[100,50],[100,100]]));

(%o5)
matrix([10,5,0.0,1.0,-1.0],[10,10,7.5,0.5,-0.5],[50,25,0.0,1.0,-1.0],[50,50,
37.5,0.5,-0.5],[100,50,0.0,1.0,-1.0],  [100,100,75.0,0.5,-0.5])

--bw=

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```