       Re: Matrices as operators

• To: mathgroup at smc.vnet.net
• Subject: [mg123214] Re: Matrices as operators
• From: Ray Koopman <koopman at sfu.ca>
• Date: Sat, 26 Nov 2011 06:48:12 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```----- Christopher Young <cy56 at comcast.net> wrote:
> On Nov 25, 2011, at 6:17 PM, Ray Koopman wrote:
>
>> This is simpler.  Does it do what you want?
>> Note that 'mat' can be a ragged array.
>> Mapping at {-1} preserves its shape, whatever it may be.
>>
>> In:= op[mat_,t_] := Map[#@t&, mat, {-1}]
>>
>> In:= op[ { {Sin, Cos}, Tan, whatever }, t ]
>>
>> Out= { {Sin[t], Cos[t]}, Tan[t], whatever[t] }
>
> Thanks very much, this is very close to what I need.
> I just need to keep the "[t]" from being added to numbers.
>
> In:= op[mat_, t_] := Map[#1[t] &, mat, {-1}]
>
> In:= op[{{Sin, Cos}, Tan, {Cos, 0, 1}}, t]
>
> Out= {{Sin[t], Cos[t]}, Tan[t], {Cos[t], 0[t], 1[t]}}

This won't try to interpret a number as a function:

In:= op[mat_, t_] := Map[If[NumericQ@#, #, #@t] &, mat, {-1}]

In:= op[{{Sin, Cos}, Tan, {Cos, 0, 1}}, t]

Out= {{Sin[t], Cos[t]}, Tan[t], {Cos[t], 0, 1}}

```

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