Access:

!´LFFT IFFT

 

( ´is the left-shift of the Pkey).

Input/Output:

 

 

 

 

 

 

 

 

 

 

 

 

Level 1/Argument 1

 

Level 1/Item 1

 

 

 

 

 

 

 

[ array ]1

→

[ array ]2

See also:

FFT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IFT

Command

 

 

 

Type:

 

 

 

Description:

IF-THEN Command: Executes obj if T/F is nonzero. Discards obj if T/F is zero.

 

IFT lets you execute in stack syntax the decision-making process of the IF … THEN … END

 

conditional structure. The “true clause” is obj in argument 2 (level 1).

 

Access:

!°BRANCH IFT

 

( °is the left-shift of the Nkey).

Input/Output:

 

 

 

 

 

 

 

 

 

 

 

 

Level 2/Argument 1

Level 1/Argument 2

Level 1/Item 1

 

 

 

 

 

 

 

 

T/F

obj

→

It depends!

 

« X 0 >

 

Example:

"Positive" IFT » puts "Positive" in level 1 if X contains a positive

 

real number.

 

 

 

See also:

IFTE

 

 

 

 

 

 

 

 

 

IFTE

Function

 

 

 

Type:

 

 

 

Description:

IF-THEN-ELSE Function: Executes the obj in argument 2 or level 2 if T/F is nonzero. Executes

 

the obj in argument 3 or level 1 if T/F is zero.

 

 

IFTE lets you execute in stack syntax the decision-making process of the IF … THEN … ELSE

…END conditional structure. The “true clause” is objtrue in argument 2 or level 2. The “false clause” is objfalse in argument 3 or level 1.

IFTE is also allowed in algebraic expressions, with the following syntax:

IFTE(test,true-clause,false-clause)

When an algebraic containing IFTE is evaluated, its first argument test is evaluated to a test result. If it returns a nonzero real number, true-clauseis evaluated. If it returns zero, false-clauseis evaluated.

Access:

!°BRANCH LIFTE

( °is the left-shift of the Nkey).

 

Input/Output:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Level 3/Argument 1

Level 2/Argument 2

Level 1/Argument 3

 

Level 1/Item 1

 

 

 

 

 

 

 

 

 

T/F

objtrue

objfalse

→

It depends!

 

The command

 

Example 1:

sequence X 0 Š "Positive" "Negative" IFTE leaves

 

"Positive" on the stack if X contains a non-negative real number, or "Negative" if

 

X contains a negative real number.

 

 

 

Example 2:

The algebraic 'IFTE(X‹0,SIN(X)/X,1)' returns the value of sin(x)/x, even for x = 0,

 

which would normally cause an Infinite Result error.

 

 

 

See also:

IFT

 

 

 

 

 

 

 

 

 

 

 

ILAP

 

 

 

 

 

 

Type:

Function

 

 

 

 

Description: Returns the inverse Laplace transform of an expression. The expression must evaluate to a rational fraction.

3-114 Full Command and Function Reference