- #1
aihaike
- 52
- 0
Dear all,
In order to develop in cos in sin terms and then simplify the expression
<br /> S=\left(q_{j}\cos\mathbf{k}\centerdot\mathbf{r}_{j}\right)\left(\sum_{j}^{N}q_{j}exp\mathbf{-k}\centerdot\mathbf{r}_{j}\right)-\left(q_{j}\cos\mathbf{-k}\centerdot\mathbf{r}_{j}\right)\left(\sum_{j}^{N}q_{j}exp\mathbf{k}\centerdot\mathbf{r}_{j}\right)<br />
I'd like to put the expression
<br /> Q=\sum_{j}^{N}q_{j}exp\mathbf{-k}\centerdot\mathbf{r}_{j}<br />
in a variable.
Does anyone know how to proceed ?
Thanks,
Éric.
In order to develop in cos in sin terms and then simplify the expression
<br /> S=\left(q_{j}\cos\mathbf{k}\centerdot\mathbf{r}_{j}\right)\left(\sum_{j}^{N}q_{j}exp\mathbf{-k}\centerdot\mathbf{r}_{j}\right)-\left(q_{j}\cos\mathbf{-k}\centerdot\mathbf{r}_{j}\right)\left(\sum_{j}^{N}q_{j}exp\mathbf{k}\centerdot\mathbf{r}_{j}\right)<br />
I'd like to put the expression
<br /> Q=\sum_{j}^{N}q_{j}exp\mathbf{-k}\centerdot\mathbf{r}_{j}<br />
in a variable.
Does anyone know how to proceed ?
Thanks,
Éric.