EXAMPLE IGOR PROGRAM WITH PROGRAMMING CONVENTIONS

#pragma rtGlobals=1		// Use modern global access method.

// Igor Programming Conventions for CHEM-5181 -- Mass Spec and Chromatography at CU-Boulder
// Version 2, Ingrid 20-Aug-2009
// These are good practices from experience of many people. You'll have to develop your own eventually
// but this is a good set to get started


// CONSTANTS
// Declare constants at the top of your procedure file only. Use ALL CAPS for constant names, so that
// you can easily recognize them in your code.  Include units in the name.

CONSTANT AMU_kg = 1.6603e-27			// amu in kg
CONSTANT UNITQ_C = 1.6e-19			// elementary charge in C
CONSTANT NUMPTS = 100			// Number of points for my waves

// Don't use all caps for anything else in your programs, so that you don't confuse constants with 
// variables, function names etc. Use mixed case, e.g. ForceX or TimeInQuad.

// Global Variable -- use g as a prefix so that you can easily recognize these in your code
// This variable remembers its value at all times -- use only if needed, as this can create painful bugs
Variable/G	gMyGlobal1		

// Function should have a good name that describes what it does.  (Note that these functions have bad 
// names for simplicity.)

Function MyFunction(Input1, input2)

	// Everything in a function should be indented by 1 tab
	// Input variables need to be declared first
	Variable Input1, Input2	// Try to always comment what things mean, and to give them
				// meaningful names with units (e.g., vel_0_m_s, accel_m_s2).
// You will come back to use your code after a while
				// and it will take a lot less time to relearn it if the code is READABLE
			      // Quote from experienced programmer: "Write programs for ease of reading"

	NVAR gMyGlobal1     // You need this statement in order to be able to access the global variable				         // inside this function; without this you would get a compilation error
							
	Variable InternalVar1, InternalVar2 = 1	// These variables are internal ("local") to your function							// Their values are lost when the function exits

	Variable iTime			// Index for For loop, give them meaningful names, not just i, j...
	
	Make/O/N=(NUMPTS)	 wPosX_m, wPosY_m// Waves for X and Y position of an ion, with units. 
          // Use the w prefix so that you can easily tell in 
         // your code what is a wave

	gMyGlobal1 = 10		// Initialize the global variable	

	// Use extra spaces in loop conditions and in calculations for ease of readability)										
	

For (iTime = 0; iTime < NUMPTS ; iTime += 1)
	
	         // Everything inside of a loop (or If statement) should be indented by 1 tab, to make the code
	         // easily readable
	
		wPosX_m[iTime + 1] = wPosX_m[iTime] + (InternalVar1 + 1) * InternalVar2 
	
	EndFor
							
	// Return statement. The function returns the position of the ion in the last time step
	// If you execute the function in the command line as Print MyFunction(2, 2)  it should print 100									
	Return wPosX_m[NUMPTS - 1]

End Function


// Master function, exemplifies how the returned value from a function can be used
// I.e. your function above returns a value and can be used in a formula, much like sin(2) or sqrt(2)
// It should print 20 to the command line when executed

Function MyMasterFunction()

	Print MyFunction(2,2) / 10 + MyFunction(1,1) * 0.1

End Function