The first week will bedevoted to getting set-up and introducing you to a few IDLstatements. By entering IDL (or IDLDE) at your system prompt orclicking on the IDLicon, you can start entering the commandslisted in the exercises on Chapter 3.

In Chapter 3, you wereintroduced to
§ print procedure which performs unformatted/formattedoutput to the defined standard output stream, your terminalwindow
§ help procedure which provides you information on theparticular variable or expression
§ various graphic procedures as plot, contour, surface,shade_surf

Notes:
Variables are not required to be pre-declared
Commands and variable names are not case sensitive.
Commas are used as delimiters to separate items as arguments,parameters, etc.
Semicolon is used to specify comments – IDL ignores the textfollowing a semicolon
Data types (not complete list):

Type Size Type Function Array FunctionArrayFunction where
each element becomes set to the value of its one-dimensionalsubscript
byte, 1B 8 BYTE( ) BYTARR( ) BINDGEN()
integer, 1 16 FIX( ) INTARR( ) INDGEN()
long, 1L 32 LONG( ) LONARR( ) LINDGEN()
float, 1.0, 1.0E+0 32 FLOAT( ) FLTARR() FINDGEN( )
double, 1.0D, 1.0D+0 64 DOUBLE( ) DBLARR() DINDGEN( )
complex 64 COMPLEX( ) COMPLEX( ) CINDGEN()
String, “1”, ‘1’STRING() STRARR( ) SINDGEN( )

Arithmetic operators (notcomplete list)

+ addition
/ division
^ exponentiation
* multiplication (scalar)
– subtraction/Negation
mod modulus

Enter the followingcommands at the IDL prompt and report the outputresults:

print, 3 + 5 * (2 +4)^3
print, 3 + 5.0*(2 + 4)^3
print, 3 + 5.0*(2 + 4)^3 mod 3
print, (3 + 5.0 * (2 + 4)^3) mod 3

print,“Theoutput of FINDGEN(10) is”,findgen(10)

print,“Theoutput of FINDGEN(10) is”,findgen(10),format=’(A,1X,10F5.2)’

x =indgen(5); x isdefined as a one-dimensional integer array with 5 elements
help, x
print, x[0], x[4]; subscripts ofarrays start at 0
x = float(x) + 1.0; x is converted to afloating-point array
help, x
print, x[0], x[3]

Explain thefollowing

arguments for thecontour procedure (see IDL online help assistant):

/follow

/fill

HW #1

Printtheexpression:
Print the expression:
Print the expression:

4. Print a one-dimensional array of 10 numbers, then print the 7-thand 9-th elements of the array.

5. Print a two-dimensionalarray of elements that consists of 5 columns and 6 rows. Print theelement of the 4-thhh column and 5-th row.

6. From homework exercise4, print

7. Plotfor an one-dimensional array of 12 elements. Try the procedureagain by inserting the WINDOW command and choosing random valuesfor‘xsize’ and ‘ysize’ for 3times.

8. Now plot the same function by simply changing the order of thearguments.

EXPLORE:
1)2)
IDL>arr=[2,3,4,5,6]IDL>arr=[4.32,7.89,-1.25,-2.93]
IDL>help,arrIDL>print, fix(arr)

What is the meaning of the‘fix’ function?