Download Basic operations in LabVIEW MathScript

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Basic operations in LabVIEW
MathScript
∗
Anthony Antonacci
Based on Basic operations in MATLAB† by
Anders Gjendemsjø
Darryl Morrell
This work is produced by OpenStax-CNX and licensed under the
‡
Creative Commons Attribution License 2.0
Abstract
This module covers basic operations in LabVIEW MathScript.
1 Basic Operations on Numbers
LABVIEW MATHSCRIPT has many arithmetic operations and functions built in. Most of them are straightforward to use. The Table (Table 1: Common scalar mathematical operations in LABVIEW MATHSCRIPT)
below lists some commonly used scalar operations; in this table, x and y are scalars. (A scalar is a single
number.)
Common scalar mathematical operations in LABVIEW MATHSCRIPT
Operation
LABVIEW MATHSCRIPT
x−y
x-y
x+y
x+y
xy
x*y
x
y
x/y
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∗ Version
1.1: Aug 2, 2006 12:56 pm -0500
† http://cnx.org/content/m13439/1.3/
‡ http://creativecommons.org/licenses/by/2.0/
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x^y
xy
x
exp(x)
log10 (x)
log10(x)
ln (x)
log(x)
log2 (x)
log2(x)
e
Table 1
Expressions are formed from numbers, variables, and these operations. The operations have dierent
precedences. The ^ operation has the highest precedence; ^ operations are evaluated before any other
operations. Multiplication and division have the next highest precedence, and addition and subtraction have
the lowest precedence. Precedence is altered by parentheses; expressions within parenthesesare evaluated
before expressions outside parentheses.
Example 1
The Table (Table 2: Example LABVIEW MATHSCRIPT Expressions) below shows several mathematical formulas, the corresponding LABVIEW MATHSCRIPT expressions, and the values that
LABVIEW MATHSCRIPT would compute for the expressions.
Example LABVIEW MATHSCRIPT Expressions
formula
LABVIEW MATHSCRIPT
Expression
Computed Value
52 + 42
5^2+4^2
41
2
(5+4)^2
81
2+3
4−5
(2 + 3)/(4 - 5)
-5
log10 (100)
log10(100)
2
ln (4 × (2 + 3))
log(4*(2+3))
2.9957
(5 + 4)
Table 2
2 Basic Operations on Matrices
In addition to scalars, LABVIEW MATHSCRIPT can operate on matrices. Some common matrix operations
are shown in the Table (Table 3: Common matrix mathematical operations in LABVIEW MATHSCRIPT)
below; in this table, M and N are matrices.
Common matrix mathematical operations in LABVIEW MATHSCRIPT
Operation
LABVIEW MATHSCRIPT
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M*N
MN
M
−1
inv(M)
T
M'
M
det(M )
det(M)
Table 3
LABVIEW MATHSCRIPT functions length and size are used to nd the dimensions of vectors and
matrices, respectively.
LABVIEW MATHSCRIPT can perform an operation on each element of a vector or matrix. To perform
an arithmetic operation on each element in a vector (or matrix), rather than on the vector (matrix) itself,
then the operator should be preceded by ".", e.g .*, .^ and ./.
Example2





Let A = 


1
1
1
1
1
1
1
1
. Then A^2 will return AA = 
2
2
2
2
, while A.^2 will return 
12
12
12
12
=

.
Example 3
1
. This can be easily be done
Given a vector x, compute a vector y having elements y (n) = sin(x(n))
in LABVIEW MATHSCRIPT by typing y=1./sin(x) Note that using / in place of ./ would result
in the (common) error Matrix dimensions must agree.
3 Complex numbers
LABVIEW MATHSCRIPT has excellent support for complex numbers with several built-in functions available. The imaginary unit is denoted by i or (as preferred in electrical engineering) j. To create complex
variables z1 = 7 + i and z2 = 2eiπ simply enter z1 = 7 + j and z2 = 2*exp(j*pi)
The Table below gives an overview of the basic functions for manipulating complex numbers, where z is
a complex number.
Manipulating complex numbers in LABVIEW MATHSCRIPT
LABVIEW MATHSCRIPT
Re(z )
Im(z )
real(z)
|z|
abs(z)
Angle(z )
angle(z)
imag(z)
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conj(z)
z∗
Table 4
4 Other Useful Details
• A semicolon added at the end of a line tells LABVIEW MATHSCRIPT to suppress the command
output to the display.
• LABVIEW MATHSCRIPT Version 1.0 is case sensitive for both variables and functions; for example,
b and B are dierent variables and LABVIEW MATHSCRIPT will recognize the built-in function sum
but not SUM. In previous versions, LABVIEW MATHSCRIPT was not case sensitive for function names.
• Often it is useful to split a statement over multiple lines. To split a statement across multiple lines,
enter three periods ... at the end of the line to indicate it continues on the next line.
Example 4
Splitting y = a + b + c over multiple lines.
y = a...
+ b...
c;
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