DEFINING FUNCTIONS

f[x_] := x^2

f[a+b]

f[2.2]

Expand[ f[x + I y] + f[x - I y] ]

?f

Clear[f]

f[2]

g[x_,y_] := Sqrt[x] + Sqrt[y]

g[a+b,a-b]

mysum[s_,n_] := Sum[ 1/i^s, {i,1,n} ]

N[ mysum[4,100] ]

N[Pi^4/90]

f[x]+f[y] /. x -> 2

f[a b] + f[u v] /. f[x_ y_] -> f[x] + f[y]

LISTS AND TABLES

Table[ i, {i,10} ]

x^%

D[%,x]

% /. x -> 1

Table[ Sin[n Pi/4], {n,0,8} ]

N[%]

mytable = Table[ x^(i+j+k), {i,0,2}, {j,0,2}, {k,0,2} ]

mytable[[3,3,3]]

{{1,1,1,1},{2,2,2,2},{3,3,3,3},{4,4,4,4}}

% // TableForm

Table[ Random[], {1000} ] ;

ListPlot[%]