       Re: Lists of Equations

• To: mathgroup at smc.vnet.net
• Subject: [mg106339] Re: Lists of Equations
• From: dh <dh at metrohm.com>
• Date: Fri, 8 Jan 2010 06:28:57 -0500 (EST)
• References: <hi6svt\$9uu\$1@smc.vnet.net>

```
Hi Michael,

what you are looking for is: Thread:

yeqs = {y1'[x], y2'[x], y3'[x]};

zeqs = {z1[x], z2[x], z3[x]};

Daniel

Michael Knudsen wrote:

> Hello,

>

> I have just started using Mathematica, and I wonder what the easiest

> way to manage a large set of equations is. I have a bunch of

> differential equations

>

> y1'[x] = z1[x]

> y2'[x] = z2[x]

> ...

> yn'[x] = zn[x]

>

> and I have grouped them together in a list like

>

> eqs = {y1'[x]==z1[x], ..., yn'[x]==zn[x]}

>

> which fits perfectly as an argument to NDSolve. However, I think that,

> at a later point, I may have to use z1,...,zn separately, and I

>

> yeqs = {y1'[x],...,yn'[x]}

> zeqs = {z1[x],...,zn[x]}

>

> and them combine them. What I would really like is something like

>

> yeqs + "==" + zeqs

>

> but I can't seem to find any list operation that will do that. Any

> help is appreciated.

>

> Thanks,

> Michael Knudsen

>

```

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