Mario February 2016
### Terms of an equation in different order

I'm using wxMaxima 15.08.1 (win 10) and when I input this equation

```
/* [wxMaxima: input start ] */a*x+b*y+c*z=0;
```

I get this:

```
/* [wxMaxima: input end ] */cz+by+ax=0
```

Why does it change the term's position of the expression? It seems like in descending order somehow.

Then, if I type another equation giving all coefficients the same unknown, maxima outputs it just right.

```
/* [wxMaxima: input start ] */a*x^2+b*x+c=0;
/* [wxMaxima: input end ] */ax^2+bx+x=0
```

Maxima has its own idea of the canonical ordering of terms in "+" and "*" expressions. The canonical ordering is expressed by the function `ordergreatp`

(equivalently `orderlessp`

) which tells if one term comes after (respectively, before) another term. If you apply `sort`

to a list of terms, they are sorted, by default, according to the canonical order.

By default, "+" terms are displayed in reverse order (reverse of the canonical order). When the global variable `powerdisp`

is `true`

, "+" terms are displayed in the canonical order. You can decide whether one order or the other works better for you.

```
(%i2) powerdisp;
(%o2) false
(%i3) a*x + b*y + c*z;
(%o3) c z + b y + a x
(%i4) a*x^2 + b*x + c;
2
(%o4) a x + b x + c
(%i7) powerdisp : true $
(%i8) a*x + b*y + c*z;
(%o8) a x + b y + c z
(%i9) a*x^2 + b*x + c;
2
(%o9) c + b x + a x
```

Asked in February 2016

Viewed 2,698 times

Voted 7

Answered 1 times

Viewed 2,698 times

Voted 7

Answered 1 times