1 | initial version |

You are trying to use the symbolic sum notation (intended for *variable* limits), but your sum is an ordinary one.

Also, indices start from `0`

in Python and SageMath.

So instead of e.g.

```
sum(area[i] * sin(2*alpha[i])^2, i, 1, 5)
```

it should be e.g.

```
sum(area[i] * sin(2*alpha[i])^2 for i in range(5))
```

Note also that you can do things like

```
n = 5
alpha = vector([var('alpha_%d' % (k+1)) for k in range(n)])
```

to save yourself some typing.

2 | No.2 Revision |

~~You ~~As part of the symbolic summation you are trying to ~~use the symbolic sum notation (intended for ~~access e.g. `alpha[i]`

where `i`

is an indeterminate *variable*~~ limits), but your sum is an ~~; that doesn't work. Instead you should use the ordinary ~~one.~~

summation. Also, indices start from `0`

in Python and SageMath.

So instead of e.g.

```
sum(area[i] * sin(2*alpha[i])^2, i, 1, 5)
```

it should be e.g.

```
sum(area[i] * sin(2*alpha[i])^2 for i in range(5))
```

Note also that you can do things like

```
n = 5
alpha = vector([var('alpha_%d' % (k+1)) for k in range(n)])
```

to save yourself some typing.

Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.