Re: problem with"Re" syntax

• To: mathgroup at smc.vnet.net
• Subject: [mg116875] Re: problem with"Re" syntax
• From: Peter Pein <petsie at dordos.net>
• Date: Thu, 3 Mar 2011 05:57:03 -0500 (EST)
• References: <ikan2k\$cdr\$1@smc.vnet.net>

```Am 26.02.2011 12:10, schrieb tarun dutta:
> c[i_][t] = a[i][t] + I*b[i][t];
> d[i_][t] = g[i][t] + I*h[i][t];
> del = Together[Sum[Sqrt[i]*d[i - 1][t]*d[i][t], {i, 0, 5}]]
> Re[del]
>
> the problem is that after executing the program, as output I am not
> able to get only the real part of the expression(del).the output
> contains the whole expression though i am using "Re" term.
>
> some valuable insight will be much appreciated.
> regards,
> tarun
>
in this case too: tell Mathematica that everything except complexes is real:
In[1]:= c[i_][t]=a[i][t]+I*b[i][t];
d[i_][t]=g[i][t]+I*h[i][t];
del=Together[Sum[Sqrt[i]*d[i-1][t]*d[i][t],{i,0,5}]]
Simplify[Re[del],Element[Except[_Complex],Reals]]

Out[3]= g[0][t] g[1][t]+Sqrt[2] g[1][t] g[2][t]+Sqrt[3] g[2][t]
g[3][t]+2 g[3][t] g[4][t]+Sqrt[5] g[4][t] g[5][t]+I g[1][t] h[0][t]+I
g[0][t] h[1][t]+I Sqrt[2] g[2][t] h[1][t]-h[0][t] h[1][t]+I Sqrt[2]
g[1][t] h[2][t]+I Sqrt[3] g[3][t] h[2][t]-Sqrt[2] h[1][t] h[2][t]+I
Sqrt[3] g[2][t] h[3][t]+2 I g[4][t] h[3][t]-Sqrt[3] h[2][t] h[3][t]+2 I
g[3][t] h[4][t]+I Sqrt[5] g[5][t] h[4][t]-2 h[3][t] h[4][t]+I Sqrt[5]
g[4][t] h[5][t]-Sqrt[5] h[4][t] h[5][t]

Out[4]= g[0][t] g[1][t]+Sqrt[2] g[1][t] g[2][t]+Sqrt[3] g[2][t]
g[3][t]+2 g[3][t] g[4][t]+Sqrt[5] g[4][t] g[5][t]-h[0][t]
h[1][t]-Sqrt[2] h[1][t] h[2][t]-Sqrt[3] h[2][t] h[3][t]-2 h[3][t]
h[4][t]-Sqrt[5] h[4][t] h[5][t]

P²

```

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