Texas Instruments TITANIUM TI-89 - Manual (Page 830)

830 Appendix A: Functions and Instructions
identity() MATH/Matrix menu
identity( expression )
⇒ ⇒ ⇒ ⇒ matrix
Returns the identity matrix with a dimension of
expression .
expression must evaluate to a positive integer.
identity(4) ¸







 1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
If CATALOG
If Boolean expression If Boolean expression Then
statement block
EndIf
If Boolean expression evaluates to true, executes
the single statement statement or the block of
statements block before continuing execution.
If Boolean expression evaluates to false, continues
execution without executing the statement or
block of statements.
block can be either a single statement or a
sequence of statements separated with the “:”
character.
Program segment:
©
:If x<0
:Disp "x is negative"
©
—
or —
©
:If x<0 Then
: Disp "x is negative"
: abs(x)! x
:EndIf
©
If Boolean expression Then
block1
Else
block2
EndIf
If Boolean expression evaluates to true, executes
block1 and then skips block2 .
If Boolean expression evaluates to false, skips block1
but executes block2 .
block1 and block2 can be a single statement.
Program segment:
©
:If x<0 Then
: Disp "x is negative"
: Else
: Disp "x is positive or zero"
:EndIf
©
If Boolean expression1 Then
block1
ElseIf Boolean expression2 Then
block2
©©©©
ElseIf Boolean expressionN Then
blockN
EndIf
Allows for program branching. If Boolean
expression1 evaluates to true, executes block1 . If
Boolean expression1 evaluates to false, evaluates
Boolean expression2 , etc.
Program segment:
©
:If choice=1 Then
: Goto option1
: ElseIf choice=2 Then
: Goto option2
: ElseIf choice=3 Then
: Goto option3
: ElseIf choice=4 Then
: Disp "Exiting Program"
: Return
:EndIf
©
imag() MATH/Complex menu
imag( expression1 ) ⇒ ⇒ ⇒ ⇒ expression
imag( expression1 ) returns the imaginary part of
the argument.
Note: All undefined variables are treated as real
variables. See also
real() .
imag(1+2 i ) ¸ 2
imag(z) ¸ 0
imag(x+ i y) ¸ y
imag( list1 )
⇒ ⇒ ⇒ ⇒ list
Returns a list of the imaginary parts of the
elements.
imag({ë3,4ëi,i}) ¸ {0 л 1 1}