#toc
Table of Contents
#toc0
Name
vector -  Vector data type for Tcl
#toc1
Synopsis
vector
create
vecName
?
vecName
...? ?
switches
?
vector destroy
vecName
?
vecName
...?
vector
expr
expression
vector names
?
pattern
...?
#toc2
Description
The
vector
command creates
a vector of floating point values.  The vector's components can be manipulated
in three ways: through a Tcl array variable, a Tcl command, or the C API.
#toc3
Introduction
A vector is simply an ordered set of numbers.  The components
of a vector are real numbers, indexed by counting numbers.
Vectors are common
data structures for many applications.  For example, a graph may use two
vectors to represent the X-Y coordinates of the data plotted.  The graph
will automatically be redrawn when the vectors are updated or changed. By
using vectors,  you can separate data analysis from the graph widget.  This
makes it easier, for example, to add data transformations, such as splines.
It's possible to plot the same data to in multiple graphs, where each graph
presents a different view or scale of the data.
You could try to use Tcl's
associative arrays as vectors.  Tcl arrays are easy to use.  You can access
individual elements randomly by specifying the index, or the set the entire
array by providing a list of index and value pairs for each element.  The
disadvantages of  associative arrays as vectors lie in the fact they are
implemented as hash tables.
·
There's no implied ordering to the associative
arrays.  If you used vectors for plotting, you would want to insure the
second component comes after the first, an so on.  This isn't possible since
arrays are actually hash tables.  For example, you can't get a range of values
between two indices.  Nor can you sort an array.
·
Arrays consume lots of memory
when the number of elements becomes large (tens of thousands).  This is
because each element's index and value are stored as strings in the hash
table.
·
The C programming interface is unwieldy.  Normally with vectors, you
would like to view the Tcl array as you do a C array, as an array of floats
or doubles.  But with hash tables, you must convert both the index and value
to and from decimal strings, just to access an element in the array.  This
makes it cumbersome to perform operations on the array as a whole.
The
vector
command tries to overcome these disadvantages while still retaining the
ease of use of Tcl arrays.  The
vector
command creates both a new Tcl command
and associate array which are linked to the vector components.  You can
randomly access vector components though the elements of array.  Not have
all indices are generated for the array, so printing the array (using the
parray
procedure) does not print out all the component values.  You can
use the Tcl command to access the array as a whole.  You can copy, append,
or sort vector using its command.  If you need greater performance, or customized
behavior, you can write your own C code to manage vectors.
#toc4
Example
You create
vectors using the
vector
command and its
create
operation.
# Create a new vector.
vector create y(50)
This creates a new vector named
y
.  It has fifty components, by default,
initialized to
0.0
.  In addition, both a Tcl command and array variable,
both named
y
, are created.  You can use either the command or variable to
query or modify components of the vector.
# Set the first value.
set y(0) 9.25
puts "y has [y length] components"
The array
y
can be used to read or set individual components of the vector.
Vector components are indexed from zero.  The array index must be a number
less than the number of components.  For example, it's an error if you try
to set the 51st element of
y
.
# This is an error. The vector only has 50 components.
set y(50) 0.02
You can also specify a range of indices using a colon (:) to separate the
first and last indices of the range.
# Set the first six components of y
set y(0:5) 25.2
If you don't include an index, then it will default to the first and/or
last component of the vector.
# Print out all the components of y
puts "y = $y(:)"
There are special non-numeric indices.  The index
end
, specifies the last
component of the vector.  It's an error to use this index if the vector is
empty (length is zero).  The index
++end
can be used to extend the vector
by one component and initialize it to a specific  value.  You can't read
from the array using this index, though.
# Extend the vector by one component.
set y(++end) 0.02
The other special indices are
min
and
max
.  They return the current smallest
and largest components of the vector.
# Print the bounds of the vector
puts "min=$y(min) max=$y(max)"
To delete components from a vector, simply unset the corresponding array
element. In the following example, the first component of
y
is deleted.
All the remaining components of
y
will be moved down by one index as the
length of the vector is reduced by one.
# Delete the first component
unset y(0)
puts "new first element is $y(0)"
The vector's Tcl command can also be used to query or set the vector.
# Create and set the components of a new vector
vector create x
x set { 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 }
Here we've created a vector
x
without a initial length specification. In
this case, the length is zero.  The
set
operation resets the vector, extending
it and setting values for each new component.
There are several operations
for vectors.  The
range
operation lists the components of a vector between
two indices.
# List the components
puts "x = [x range 0 end]"
You can search for a particular value using the
search
operation.  It returns
a list of indices of the components with the same value.  If no component
has the same value, it returns
""
.
# Find the index of the biggest component
set indices [x search $x(max)]
Other operations copy, append, or sort vectors.  You can append vectors
or new values onto an existing vector with the
append
operation.
# Append assorted vectors and values to x
x append x2 x3 { 2.3 4.5 } x4
The
sort
operation sorts the vector.  If any additional vectors are specified,
they are rearranged in the same order as the vector. For example, you could
use it to sort data points represented by x and y vectors.
# Sort the data points
x sort y
The vector
x
is sorted while the components of
y
are  rearranged so that
the original x,y coordinate pairs are retained.
The
expr
operation lets
you perform arithmetic on vectors.   The result is stored in the vector.
# Add the two vectors and a scalar
x expr { x + y }
x expr { x * 2 }
When a vector is modified, resized, or deleted, it may trigger call-backs
to notify the clients of the vector.  For example, when a vector used in
the
graph
widget is updated, the vector automatically notifies the widget
that it has changed.  The graph can then redrawn itself at the next idle
point.  By default, the notification occurs when Tk is next idle.  This way
you can modify the vector many times without incurring the penalty of the
graph redrawing itself for each change.  You can change this behavior using
the
notify
operation.
# Make vector x notify after every change
x notify always
...
# Never notify
x notify never
...
# Force notification now
x notify now
To delete a vector, use the
vector delete
command.   Both the vector and
its corresponding Tcl command are destroyed.
# Remove vector x
vector destroy x
#toc5
Syntax
Vectors are created using the
vector create
operation.   Th
create
operation can be invoked in one of three forms:
vector create
vecName
This
creates a new vector
vecName
which initially has no components.
vector create
vecName
(
size
)
This second form creates a new vector which will contain
size
number of components.  The components will be indexed starting from
zero (0). The default value for the components is
0.0
.
vector create
vecName
(
first
:
last
)
The last form creates a new vector of indexed
first
through
last
.
First
and
last
can be any integer value so long as
first
is less than
last
.
Vector
names must start with a letter and consist of letters, digits, or underscores.
# Error: must start with letter
vector create 1abc
You can automatically generate vector names using the "
#auto
" vector name.
The
create
operation will generate a  unique vector name.
set vec [vector create #auto]
puts "$vec has [$vec length] components"
#toc6
Vector Indices
Vectors are indexed by integers.  You can access the individual
vector components via its array variable or Tcl command.  The string representing
the index can be an integer, a numeric expression, a range, or a special
keyword.
The index must lie within the current range of the vector, otherwise
an an error message is returned.  Normally the indices of a vector are start
from 0.  But you can use the
offset
operation to change a vector's indices
on-the-fly.
puts $vecName(0)
vecName offset -5
puts $vecName(-5)
You can also use numeric expressions as indices.  The result of the expression
must be an integer value.
set n 21
set vecName($n+3) 50.2
The following special non-numeric indices are available:
min
,
max
,
end
,
and
++end
.
puts "min = $vecName($min)"
set vecName(end) -1.2
The indices
min
and
max
will return the minimum and maximum values of the
vector.  The index
end
returns the value of the  last component in the vector.
The index
++end
is used to append new value onto the vector.  It automatically
extends the vector by one component and sets its value.
# Append an new component to the end
set vecName(++end) 3.2
A range of indices can be indicated by a colon (:).
# Set the first six components to 1.0
set vecName(0:5) 1.0
If no index is supplied the first or last component is assumed.
# Print the values of all the components
puts $vecName(:)
#toc7
Vector Operations
vector create
vecName
?(
size
)?... ?
switches
?
The
create
operation
creates a new vector
vecName
.  Both a Tcl command and array variable
vecName
are also created.  The name
vecName
must be unique, so another Tcl command
or array variable can not already exist in that scope.  You can access the
components of the vector using its variable.  If you change a value in the
array, or unset an array element, the vector is updated to reflect the
changes.  When the variable
vecName
is unset, the vector and its Tcl command
are also destroyed.
The vector has optional switches that affect how the
vector is created. They are as follows:
-variable
varName
Specifies the name
of a Tcl variable to be mapped to the vector. If the variable already exists,
it is first deleted, then recreated.  If
varName
is the empty string, then
no variable will be mapped. You can always map a variable back to the vector
using the vector's
variable
operation.
-command
cmdName
Maps a Tcl command
to the vector. The vector can be accessed using
cmdName
and one of the
vector instance operations.   A Tcl command by that name cannot already
exist. If
cmdName
is the empty string, no command mapping will be made.
-watchunset
boolean
Indicates that the vector should automatically delete itself if
the variable associated with the vector is unset.  By default, the vector
will not be deleted.  This is different from previous releases.  Set
boolean
to "true" to get the old behavior.
vector destroy
vecName
?
vecName...
?
vector
expr
expression
All binary operators take vectors as operands (remember
that numbers are treated as one-component vectors).  The exact action of
binary operators depends upon the length of the second operand.  If the
second operand has only one component, then each element of the first vector
operand is computed by that value.  For example, the expression "x * 2"
multiples all elements of the vector x by 2.  If the second operand has
more than one component, both operands must be the same length.  Each pair
of corresponding elements are computed.  So "x + y" adds the the first components
of x and y together, the second, and so on.
The valid operators are listed
below, grouped in decreasing order of precedence:
-  !
Unary minus and logical
NOT.  The unary minus flips the sign of each component in the vector.  The
logical not operator returns a vector of whose values are 0.0 or 1.0.  For
each non-zero component 1.0 is returned, 0.0 otherwise.
^
Exponentiation.
*
/  %
Multiply, divide, remainder.
+  -
Add and subtract.
<<  >>
Left and
right shift.  Circularly shifts the values of the vector  (not implemented
yet).
<  >  <=  >=
Boolean less, greater, less than or equal, and greater than
or equal. Each operator returns a vector of ones and zeros.  If the condition
is true,  1.0 is the component value, 0.0 otherwise.
==  !=
Boolean equal
and not equal. Each operator returns a vector of ones and zeros.  If the
condition is true,  1.0 is the component value, 0.0 otherwise.
|
Bit-wise OR.
(Not implemented).
&&
Logical AND.  Produces a 1 result if both operands are
non-zero, 0 otherwise.
||
Logical OR.  Produces a 0 result if both operands
are zero, 1 otherwise.
x
?
y
:
z
If-then-else, as in C.  (Not implemented yet).
See the C manual for more details on the results produced by each operator.
All of the binary operators group left-to-right within the same precedence
level.
Several mathematical functions are supported for vectors.  Each
of the following functions invokes the math library function of the same
name; see the manual entries for the library functions for details on what
they do.  The operation is applied to all elements of the vector returning
the results.
acos
cos
hypot
sinh
asin
cosh
log
sqrt
atan
exp
log10
tan
ceil
floor
sin
tanh
Additional functions are:
abs
Returns the absolute value of each component.
random
Returns a vector of non-negative values uniformly distributed  between
[0.0, 1.0) using
drand48
. The seed comes from the internal clock of the machine
or may be  set manual with the srandom function.
round
Rounds each component
of the vector.
srandom
Initializes the random number generator using
srand48
.
The high order 32-bits are set using the integral portion of the first
vector component. All other components are ignored.  The low order 16-bits
are set to an arbitrary value.
The following functions return a single
value.
adev
Returns the average deviation (defined as the sum of the absolute
values  of the differences between component and the mean, divided by the
length of the vector).
kurtosis
Returns the degree of peakedness (fourth
moment) of the vector.
length
Returns the number of components in the vector.
max
Returns the vector's maximum value.
mean
Returns the mean value of the
vector.
median
Returns the median of the vector.
min
Returns the vector's
minimum value.
q1
Returns the first quartile of the vector.
q3
Returns the
third quartile of the vector.
prod
Returns the product of the components.
sdev
Returns the standard deviation (defined as the square root of the
variance) of the vector.
skew
Returns the skewness (or third moment) of
the vector.  This characterizes the degree of asymmetry of the vector about
the mean.
sum
Returns the sum of the components.
var
Returns the variance
of the vector. The sum of the squared differences  between each component
and the mean is computed.  The variance is  the sum divided by the length
of the vector minus 1.
The last set returns a vector of the same length
as the argument.
norm
Scales the values of the vector to lie in the range
[0.0..1.0].
sort
Returns the vector components sorted in ascending order.
vector
names
?
pattern
?
#toc8
Instance Operations
You can also use the vector's Tcl command
to query or modify it.  The general form is
vecName
operation
?
arg
?...
Both
operation
and its arguments determine the exact behavior of the command.
The operations available for vectors are listed below.
vecName
append
item
?
item
?...
Appends the component values from
item
to
vecName
.
Item
can be either
the name of a vector or a list of numeric values.
vecName
clear
Clears
the element indices from the array variable associated with
vecName
.  This
doesn't affect the components of the vector.  By default, the number of entries
in the Tcl array doesn't match the number of components in the vector.  This
is because its too expensive to maintain decimal strings for both the index
and value for each component.  Instead, the index and value are saved only
when you read or write an element with a new index.  This command removes
the index and value strings from the array.  This is useful when the vector
is large.
vecName
delete
index
?
index
?...
Deletes the
index
th component from
the vector
vecName
.
Index
is the index of the element to be deleted.  This
is the same as unsetting the array variable element
index
.  The vector is
compacted after all the indices have been deleted.
vecName
dup
destName
Copies
vecName
to
destName
.
DestName
is the name of a destination vector.
If a vector
destName
already exists, it is overwritten with the components
of
vecName
.  Otherwise a  new vector is created.
vecName
expr
expression
Computes the expression and resets the values of the vector accordingly.
Both scalar and vector math operations are allowed.  All values in expressions
are either real numbers or names of vectors.  All numbers are treated as
one component vectors.
vecName
length
?
newSize
?
Queries or resets the number
of components in
vecName
.
NewSize
is a number specifying the new size of
the vector.  If
newSize
is smaller than the current size of
vecName
,
vecName
is truncated.  If
newSize
is greater, the vector is extended and the new
components are initialized to
0.0
.  If no
newSize
argument is present, the
current length of the vector is returned.
vecName
merge
srcName
?
srcName
?...
Merges the named vectors into a single vector.  The resulting  vector is
formed by merging the components of each source vector  one index at a
time.
vecName
notify
keyword
Controls how vector clients are notified of
changes to the vector.   The exact behavior is determined by
keyword
.
always
Indicates that clients are to be notified immediately whenever the vector
is updated.
never
Indicates that no clients are to be notified.
whenidle
Indicates that clients are to be notified at the next idle point whenever
the vector is updated.
now
If any client notifications is currently pending,
they are notified immediately.
cancel
Cancels pending notifications of clients
using the vector.
pending
Returns
1
if a client notification is pending,
and
0
otherwise.
vecName
offset
?
value
?
Shifts the indices of the vector
by the amount specified by
value
.
Value
is an integer number.  If no
value
argument is  given, the current offset is returned.
vecName
populate
destName
?
density
?
Creates a vector
destName
which is a superset of
vecName
.
DestName
will include all the components of
vecName
, in addition the interval between
each of the original components will contain a
density
number of new components,
whose values are evenly distributed between the original components values.
This is useful for generating abscissas to be interpolated along a spline.
vecName
range
firstIndex
?
lastIndex
?...
Returns a list of numeric values representing
the vector components between two indices. Both
firstIndex
and
lastIndex
are  indices representing the range of components to be returned. If
lastIndex
is less than
firstIndex
, the components are listed in reverse order.
vecName
search
value
?
value
?
Searches for a value or range of values among the
components of
vecName
.  If one
value
argument is given, a list of indices
of the components which equal
value
is returned.  If a second
value
is also
provided, then the indices of all components which lie within the range
of the two values are returned. If no components are found, then
""
is returned.
vecName
set
item
Resets the components of the vector to
item
.
Item
can be
either a list of numeric expressions or another vector.
vecName
seq
start
?
finish
? ?
step
?
Generates a sequence of values starting with the value
start
.
Finish
indicates the terminating value of the sequence.   The vector
is automatically resized to contain just the sequence. If three arguments
are present,
step
designates the interval.
With only two arguments (no
finish
argument), the sequence will continue until the vector is filled.
With one argument, the interval  defaults to 1.0.
vecName
sort
?
-reverse
?
?
argName
?...
Sorts the vector
vecName
in increasing order.  If the
-reverse
flag is present, the vector is sorted in decreasing order.  If other arguments
argName
are present, they are the names of vectors which will be rearranged
in the same manner as
vecName
.  Each vector must be the same length as
vecName
.
You could use this to sort the x vector of a graph, while still retaining
the same x,y coordinate pairs in a y vector.
vecName
variable
varName
Maps
a Tcl variable to the vector, creating another means for  accessing the
vector.  The variable
varName
can't already  exist. This overrides any current
variable mapping the vector may have.
#toc9
C Language API
You can create, modify,
and destroy vectors from C code, using  library routines.   You need to
include the header file
blt.h
. It contains the definition of the structure
Blt_Vector
, which represents the vector.  It appears below.
typedef struct {
double *
valueArr
;
int
numValues
;
int
arraySize
;
double
min
,
max
;
}
Blt_Vector
;
The field
valueArr
points to memory holding the vector components.  The
components are stored in a double precision array, whose size size is represented
by
arraySize
.
NumValues
is the length of vector.  The size of the array
is always equal to or larger than the length of the vector.
Min
and
max
are minimum and maximum component values.
#toc10
Library Routines
The following
routines are available from C to manage vectors. Vectors are identified
by the vector name.
Blt_CreateVector
Synopsis:
int
Blt_CreateVector
(
interp
,
vecName
,
length
,
vecPtrPtr
)
Tcl_Interp *
interp
;
char *
vecName
;
int
length
;
Blt_Vector **
vecPtrPtr
;
Description:
Creates a new vector
vecName
with a length of
length
.
Blt_CreateVector
creates both a new Tcl command and array  variable
vecName
.  Neither a command
nor variable named
vecName
can already exist.  A pointer to the vector
is  placed into
vecPtrPtr
.
Results:
Returns
TCL_OK
if the vector is successfully
created.  If
length
is negative, a Tcl variable or command
vecName
already
exists, or memory cannot be allocated for the vector, then
TCL_ERROR
is
returned and
interp->result
will contain an error message.
Blt_DeleteVectorByName
Synopsis:
int
Blt_DeleteVectorByName
(
interp
,
vecName
)
Tcl_Interp *
interp
;
char *
vecName
;
Description:
Removes the vector
vecName
.
VecName
is the name of a vector
which must already exist.  Both the Tcl command and array variable
vecName
are destroyed.  All clients of the vector will be notified immediately that
the vector has been destroyed.
Results:
Returns
TCL_OK
if the vector is
successfully deleted.  If
vecName
is not the name a vector, then
TCL_ERROR
is returned and
interp->result
will contain an error message.
Blt_DeleteVector
Synopsis:
int
Blt_DeleteVector
(
vecPtr
)
Blt_Vector *
vecPtr
;
Description:
Removes the vector pointed to by
vecPtr
.
VecPtr
is a pointer
to a vector, typically set by
Blt_GetVector
or
Blt_CreateVector
.  Both the
Tcl command and array variable of the vector are destroyed.  All clients
of the vector will be notified immediately that the vector has been destroyed.
Results:
Returns
TCL_OK
if the vector is successfully deleted.  If
vecName
is not the name a vector, then
TCL_ERROR
is returned and
interp->result
will
contain an error message.
Blt_GetVector
Synopsis:
int
Blt_GetVector
(
interp
,
vecName
,
vecPtrPtr
)
Tcl_Interp *
interp
;
char *
vecName
;
Blt_Vector **
vecPtrPtr
;
Description:
Retrieves the vector
vecName
.
VecName
is the name of a vector
which must already exist.
VecPtrPtr
will point be set to the address of
the vector.
Results:
Returns
TCL_OK
if the vector is successfully retrieved.
If
vecName
is not the name of a vector, then
TCL_ERROR
is returned and
interp->result
will contain an error message.
Blt_ResetVector
Synopsis:
int
Blt_ResetVector
(
vecPtr
,
dataArr
,
numValues
,
arraySize
,
freeProc
)
Blt_Vector *
vecPtr
;
double *
dataArr
;
int *
numValues
;
int *
arraySize
;
Tcl_FreeProc *
freeProc
;
Description:
Resets the components of the vector pointed to by
vecPtr
.
Calling
Blt_ResetVector
will trigger the vector to dispatch notifications
to its clients.
DataArr
is the array of doubles which represents the vector
data.
NumValues
is the number of elements in the array.
ArraySize
is the
actual size of the array (the array may be bigger than the number of values
stored in it).
FreeProc
indicates how the storage for the vector component
array (
dataArr
) was allocated.  It is used to determine how to reallocate
memory when the vector is resized or destroyed.  It must be
TCL_DYNAMIC
,
TCL_STATIC
,
TCL_VOLATILE
, or a pointer to a function to free the memory
allocated for the vector array. If
freeProc
is
TCL_VOLATILE
, it indicates
that
dataArr
must be copied and saved.  If
freeProc
is
TCL_DYNAMIC
, it indicates
that
dataArr
was dynamically allocated and that Tcl should free
dataArr
if necessary.
Static
indicates that nothing should be done to release storage
for
dataArr
.
Results:
Returns
TCL_OK
if the vector is successfully resized.
If
newSize
is negative, a vector
vecName
does not exist, or memory cannot
be allocated for the vector, then
TCL_ERROR
is returned and
interp->result
will contain an error message.
Blt_ResizeVector
Synopsis:
int
Blt_ResizeVector
(
vecPtr
,
newSize
)
Blt_Vector *
vecPtr
;
int
newSize
;
Description:
Resets the length of the vector pointed to by
vecPtr
to
newSize
.
If
newSize
is smaller than the current size of the vector, it is truncated.
If
newSize
is greater, the vector is extended and the new components are
initialized to
0.0
. Calling
Blt_ResetVector
will trigger the vector to dispatch
notifications.
Results:
Returns
TCL_OK
if the vector is successfully resized.
If
newSize
is negative or memory can not be allocated for the vector,
then
TCL_ERROR
is returned and
interp->result
will contain  an error message.
Blt_VectorExists
Synopsis:
int
Blt_VectorExists
(
interp
,
vecName
)
Tcl_Interp *
interp
;
char *
vecName
;
Description:
Indicates if a vector named
vecName
exists in
interp
.
Results:
Returns
1
if a vector
vecName
exists and
0
otherwise.
If your application
needs to be notified when a vector changes, it can allocate a unique
client
identifier
for itself.  Using this identifier, you can then register a call-back
to be made whenever the vector is updated or destroyed.  By default, the
call-backs are made at the next idle point.  This can be changed to occur
at the time the vector is modified.  An application can allocate more than
one identifier for any vector.  When the client application is done with
the vector, it should free the identifier.
The call-back routine must of
the following type.
typedef void (
Blt_VectorChangedProc
) (Tcl_Interp *
interp
,
ClientData
clientData
, Blt_VectorNotify
notify
);
ClientData
is passed to this routine whenever it is called.  You can use
this to pass information to the call-back.  The
notify
argument indicates
whether the vector has been updated of destroyed. It is an enumerated type.
typedef enum {
BLT_VECTOR_NOTIFY_UPDATE
=1,
BLT_VECTOR_NOTIFY_DESTROY
=2
}
Blt_VectorNotify
;
Blt_AllocVectorId
Synopsis:
Blt_VectorId
Blt_AllocVectorId
(
interp
,
vecName
)
Tcl_Interp *
interp
;
char *
vecName
;
Description:
Allocates an client identifier for with the vector
vecName
.
This identifier can be used to specify a call-back which is triggered when
the vector is updated or destroyed.
Results:
Returns a client identifier
if successful.  If
vecName
is not the name of a vector, then
NULL
is returned
and
interp->result
will contain an error message.
Blt_GetVectorById
Synopsis:
int
Blt_GetVector
(
interp
,
clientId
,
vecPtrPtr
)
Tcl_Interp *
interp
;
Blt_VectorId
clientId
;
Blt_Vector **
vecPtrPtr
;
Description:
Retrieves the vector used by
clientId
.
ClientId
is a valid
vector client identifier allocated by
Blt_AllocVectorId
.
VecPtrPtr
will
point be set to the address of the vector.
Results:
Returns
TCL_OK
if the
vector is successfully retrieved.
Blt_SetVectorChangedProc
Synopsis:
void
Blt_SetVectorChangedProc
(
clientId
,
proc
,
clientData
);
Blt_VectorId
clientId
;
Blt_VectorChangedProc *
proc
;
ClientData *
clientData
;
Description:
Specifies a call-back routine to be called whenever the vector
associated with
clientId
is updated or deleted.
Proc
is a pointer to call-back
routine and must be of the type
Blt_VectorChangedProc
.
ClientData
is a
one-word value to be passed to the routine when it is invoked. If
proc
is
NULL
, then the client is not notified.
Results:
The designated call-back
procedure will be invoked when the vector is  updated or destroyed.
Blt_FreeVectorId
Synopsis:
void
Blt_FreeVectorId
(
clientId
);
Blt_VectorId
clientId
;
Description:
Frees the client identifier.  Memory allocated for the identifier
is released.  The client will no longer be notified when the vector is
modified.
Results:
The designated call-back procedure will be no longer be
invoked when the vector is updated or destroyed.
Blt_NameOfVectorId
Synopsis:
char *
Blt_NameOfVectorId
(
clientId
);
Blt_VectorId
clientId
;
Description:
Retrieves the name of the vector associated with the client
identifier
clientId
.
Results:
Returns the name of the vector associated
with
clientId
.  If
clientId
is not an identifier or the vector has been
destroyed,
NULL
is returned.
Blt_InstallIndexProc
Synopsis:
void
Blt_InstallIndexProc
(
indexName
,
procPtr
)
char *
indexName
;
Blt_VectorIndexProc *
procPtr
;
Description:
Registers a function to be called to retrieved the index
indexName
from the vector's array variable.
typedef double Blt_VectorIndexProc(Vector
*vecPtr);
The function will be passed a pointer to the vector.  The function
must return a double representing the value at the index.
Results:
The new
index is installed into the vector.
#toc11
C API Example
The following example opens
a file of binary data and stores it in an array of doubles. The array size
is computed from the size of the file. If the vector "data" exists, calling
Blt_VectorExists
,
Blt_GetVector
is called to get the pointer to the vector.
Otherwise the routine
Blt_CreateVector
is called to create a new vector
and returns a pointer to it. Just like the Tcl interface, both a new Tcl
command and array variable are created when a new vector is created. It
doesn't make any difference what the initial size of the vector is since
it will be reset shortly. The vector is updated when
lt_ResetVector
is called.
Blt_ResetVector makes the changes visible to the Tcl interface and other
vector clients (such as a graph widget).
#include <tcl.h>
#include <blt.h>
#toc12
Incompatibilities
In previous versions, if the array variable isn't global
(i.e. local to a Tcl procedure), the vector is automatically  destroyed
when the procedure returns.
proc doit {} {
# Temporary vector x
vector x(10)
set
x.9.html
x(9)
2.0
...
}
This has changed.  Variables are not automatically destroyed when their
variable is unset.  You can restore the old behavior by setting the "-watchunset"
switch.
#toc13
Keywords
vector, graph, widget
Table of Contents
#sect0
Name
#sect1
Synopsis
#sect2
Description
#sect3
Introduction
#sect4
Example
#sect5
Syntax
#sect6
Vector Indices
#sect7
Vector Operations
#sect8
Instance Operations
#sect9
C Language API
#sect10
Library Routines
#sect11
C API Example
#sect12
Incompatibilities
#sect13
Keywords
