Dataplot Vol 1 Vol 2

# LET

Name:
LET
Type:
Analysis Command
Purpose:
The LET command is DATAPLOT's most versatile command; it has a variety of uses:

1. evaluating functions;
2. transforming variables;
3. specifying elements of variables;
4. calculating statistics;
5. creating a sequence;
6. creating a pattern;
7. generating random numbers;
8. manipulating/sorting data;
9. defining functions;
10. carrying out math operations.
Syntax:
The syntax varies depending on the type of operation performed.
Examples:
LET A = SIN(2*PI*0.025)
LET Y = (X**LAMBDA-1)/LAMBDA
LET Y(3) = LOG(4.5)-2**3.8
LET M = MEAN Y
LET X = SEQUENCE 1 .1 10
LET X = PATTERN 1 1 2 2 3 3 FOR I = 1 1 30
LET X = NORMAL RANDOM NUMBERS FOR I=1 1 80
LET Y2 = SORT Y
LET FUNCTION F = C*EXP(-X*X/2)
LET A = INTEGRAL F WRT X FOR X 0 TO 1
Default:
None
Synonyms:
None
Note:
Help is available for the individual subcommands under LET. For example, to get lists of available subcommands, enter one of the following:

You can help for individual subommands by entering:

HELP <subcommand>

The help for the individual subcommands gives the syntax for that command.

The capabilities under LET are documented in Volume II of the Dataplot Reference Manual.

Note:
If you enter a command like

Y = NORMAL RANDOM NUMBERS FOR I = 1 1 100

Dataplot would previously return an error. The 2018/10 version of Dataplot was updated so that if a command is not matched, the command does not start with LET, and the command contains an "=" character, Dataplot will insert a "LET " at the beginning of the command string and try to match the command again.

Note that using "LET" to start the command is still the preferred syntax since this new syntax is only attempted if the first word of the command line does not match a Dataplot command. For example, "X", "R", "S", and "W" are short-cuts to existing commands, so the following will not work

X = X + 1
W = W + 1
R = R + 1
S = S + 1

Note that if the left hand side name matches an existing Dataplot command, this syntax of leaving off the LET will fail.

Related Commands:
 LET FUNCTION = Defines functions. LET STRING = Defines a string. STATUS = Displays dimension, variables, parameters, and functions. WRITE = Writes variables, parameters, and functions to the screen or to a file.
Applications:
Data Management
Implementation Date:
Pre-1987
2018/10: Syntax with "LET" omitted
Program 1:
LET A = 2
Program 2:
LET X = SEQUENCE -3.1 0.1 3.1
LET FUNCTION F = SIN(X)
LET Y = F
Program 3:
LET Y = NORMAL RANDOM NUMBERS FOR I = 1 1 100
LET YMEAN = MEAN Y
LET YSD = SD Y
Date created: 11/06/2018
Last updated: 12/04/2023