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## Re: [Reduce-algebra-developers] Commutation between sum and df.

 Re: [Reduce-algebra-developers] Commutation between sum and df. From: abpetrov - 2013-09-10 17:58:11 ```Of course, you are right. Thank you. 09.09.2013 19:48, Rainer Schöpf пишет: > On Sat, 7 Sep 2013 at 20:58 -0000, abpetrov wrote: > > > Hi, > > I tried to define an commutation rule for operation sum and operator df. > > It looks quite simple, but don't works. > > Why this rule don't work. > > Program with that rule is below, it looks simple, so without comments. > > > > > > off lower\$ > > > > operator H,k,x; > > H := sum( (1/2)*k(i)*x(i)**2, i, -infinity,infinity); > > r1 := {df(sum( ~~f, ~~i, ~~i1,~~i2),~~x(~~i)) => sum( df(f, x(i)) , i, > > i1,i2)}; > > (df(H,x(i)) where r1); > > I've just corrected the handling of the sum operator and committed. > > Besides, your rule doesn't make sense, it should be > > r1 := {df(sum(~f,~i,~i1,~i2),~x) => sum(df(f,x),i,i1,i2)}; > > Rainer > ```

 [Reduce-algebra-developers] Commutation between sum and df. From: abpetrov - 2013-09-07 14:58:35 ```Hi, I tried to define an commutation rule for operation sum and operator df. It looks quite simple, but don't works. Why this rule don't work. Program with that rule is below, it looks simple, so without comments. off lower\$ operator H,k,x; H := sum( (1/2)*k(i)*x(i)**2, i, -infinity,infinity); r1 := {df(sum( ~~f, ~~i, ~~i1,~~i2),~~x(~~i)) => sum( df(f, x(i)) , i, i1,i2)}; (df(H,x(i)) where r1); end; Best regards, Petrov Alexander. ```
 Re: [Reduce-algebra-developers] Commutation between sum and df. From: abpetrov - 2013-09-10 17:58:11 ```Of course, you are right. Thank you. 09.09.2013 19:48, Rainer Schöpf пишет: > On Sat, 7 Sep 2013 at 20:58 -0000, abpetrov wrote: > > > Hi, > > I tried to define an commutation rule for operation sum and operator df. > > It looks quite simple, but don't works. > > Why this rule don't work. > > Program with that rule is below, it looks simple, so without comments. > > > > > > off lower\$ > > > > operator H,k,x; > > H := sum( (1/2)*k(i)*x(i)**2, i, -infinity,infinity); > > r1 := {df(sum( ~~f, ~~i, ~~i1,~~i2),~~x(~~i)) => sum( df(f, x(i)) , i, > > i1,i2)}; > > (df(H,x(i)) where r1); > > I've just corrected the handling of the sum operator and committed. > > Besides, your rule doesn't make sense, it should be > > r1 := {df(sum(~f,~i,~i1,~i2),~x) => sum(df(f,x),i,i1,i2)}; > > Rainer > ```
 [Reduce-algebra-developers] Two questions From: Aditya Narayan - 2013-09-14 17:19:00 ```Hello - probably very simple things but they've been eluding me for a while now so need some help - Two questions: 1. Let's say I have a simple polynomial p:=x^4+x+1 And I want to write a procedure to format the output it as x^4+0*x^3+0*x^2+x+1 The degree is dynamic. I can easily determine coefficients and use a "write" in a loop for each term but that always adds a newline and ill get 5 lines of output instead of 1. Any suggestions? 2. How does one perform string concatenation in a reduce program? A:="s1" B:="s2" I want a new var C to be equal to the string "s1s2" Thank you! ```