### The Maxima on-line user's manual

Algebra Calculator

#### Intosum

Function: intosum (<expr>) Moves multiplicative factors outside a summation to inside. If the index is used in the outside expression, then the function tries to find a reasonable index, the same as it does for `sumcontract`. This is essentially the reverse idea of the `outative` property of summations, but note that it does not remove this property, it only bypasses it.

In some cases, a `scanmap (multthru, <expr>)` may be necessary before the `intosum`.

```(%o1)                                true
(%i2) ```

### Related Examples

##### intosum-ratexpand-sum

f:-_SAGE_VAR_t^(10*_S...

ratexpand(intosum(f));

Calculate

##### intosum-sumcontract

sumcontract(intosum((...

Calculate

##### intosum-simpsum-sum-sumcontract

a: sum(a[k], k, 1, 10...

b: sum(b[k], k, 1, 10...

sum(a+b, k, 1, 10);

Calculate

##### intosum-simpsum-sum-sumcontract

a: sum(a[k], k, 1, 10...

b: sum(b[k], k, 1, 10...

sum(a+b, k, 1, 10);

Calculate

##### intosum-simpsum-sum-sumcontract

a: sum(a[k], k, 1, 10...

b: sum(b[k], k, 1, 10...

sum(a+b, k, 1, 10);

Calculate

##### intosum-ratexpand-simpsum-sum

f:-_SAGE_VAR_t^(10*_S...

ratexpand(intosum(f))...

Calculate

##### intosum

x : (-a/2 + b/2 + c/2...

intosum(x);

Calculate

? intosum;

Calculate

##### intosum-simpsum-sum-sumcontract

a: sum(a[k], k, 1, 10...

b: sum(b[k], k, 1, 10...

sum(a+b, k, 1, 10);

Calculate

##### intosum-sumexpand-true

sumexpand: true;

x : (-a/2 + b/2 + c/2...

intosum(x);

Calculate