cos(2·Œ·@n0)
which also returns 1. To type the "@" character, use [DIAMOND] [STO] on the 89, or [2nd] [R] on the
92+.
(Credit to Hank Wu and Fabrizio)
[2.20] factor() with respect to list elements
You can use factor() to simplify expressions which include list elements. To simplify this expression
a*d[1]+b*d[1]*d[2]+d[1]*d[2]*d[3]
factor with respect to the list d, like this
factor(a*d[1]+b*d[1]*d[2]+d[1]*d[2]*d[3],d)
which returns
d[1]*(d[2]*d[3]+d[2]*b+a)
This is not fully simplified, since d[2] is not completely factored out, so factor again with respect to d[2]:
factor(d[1]*(d[2]*d[3]+d[2]*b+a),d[2])
which returns the fully factored expression
(a+(b+d[3])*d[2])*d[1]
In this example, a and b are simple expressions, but the method also works if a and b are also lists.
(Credit to Bhuvanesh Bhatt)
[2.21] Differentiation and integration fail with part()
The part() function is used to extract parts of an expression. However, in AMS 2.05, differentiation and
integration can fail when applied to part. For example, this expression
(part(ℯ^(2*t)*sin(t),2),t)
returns 0, but it should return
2*(ℯ^(2*t)
Incorrect results are also returned if you try to integrate the result of a part() operation. One
work-around is to save the result of the part() operation, then take the derivative or integral of the
saved result. This example saves the part() result to a variable called xx:
part(ℯ^(2*t)*sin(t),2)→xx
(xx,t)
The correct differentiation result is returned because the contents of xx are differentiated.
(Bug found by ES)
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