---
title: "Floating Point Math: DEBUG and Terminal Display Example"
description: "[![](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/floating-point.jpg)](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/floating-point.jpg) ##### Description Run-time floating-point operators have recently been added to Spin2’s language interpreter. These operators utilize the 32-bit IEEE-754 floating-point format.…"
url: "https://obex.parallax.com/docs/quick-bytes/propeller-2/floating-point-math-debug-and-terminal-display-example/"
updated: "2026-09-29"
category: Propeller 2
---

# Floating Point Math: DEBUG and Terminal Display Example

[![](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/floating-point.jpg)](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/floating-point.jpg)

##### Description

Run-time floating-point operators have recently been added to Spin2’s language interpreter. These operators utilize the 32-bit IEEE-754 floating-point format. Parallax’s Propeller Tool (ver 2.6.2 and higher) and FlexProp (ver. 5.9.6 and higher) support the use of floating-point math. The largest possible floating-point number that can be used is 3.4e+38.

Floating-point variables in Spin2 are really just LONG variables, but they get treated as floats when the special floating-point operators are used on them. The floating-point operators have the same precedence as the normal integer operators and often use the same symbol, but with a period after each:

```spin2
-. value        = negate
FABS value      = absolute
value *. value  = multiply
value /. value  = divide
value +. value  = add
value -. value  = negate
value <. value  = check for less-than, returns integer 0 or -1
value <=. value = check for less-than-or-equal, returns integer 0 or -1
value ==. value = check for equal, returns integer 0 or -1
value <>. value = check for not-equal, returns integer 0 or -1
value >=. value = check for greater-than-or-equal, returns integer 0 or -1
value >. value  = check for greater-than, returns integer 0 or -1
value <. value  = check for less-than, returns integer 0 or -1
FLOAT(integer)  = convert integer to float
ROUND(float)    = round float to integer
TRUNC(float)    = truncate float to integer
NAN(float)      = check float for not-a-number, returns integer 0 or -1
```

Floating-point constants must either have a decimal point and/or and “e” in them:

```spin2
1.0
-. 5.0 remember to always use the floating-point negate
1e6
1e-9 "e" can be followed by "-", "+", or just a number
6.02e+23
6.02e23
```

Floating-point values may be displayed using these functions:

```spin2
FDEC(value)
FDEC_ARRAY(hub_pointer, size)
FDEC_REG_ARRAY(reg_pointer, size)
```

**Example #1: Propeller Tool for Windows Using DEBUG **

The most simple and direct way of displaying a floating-point number is using Propeller Tool for Windows with the new **DEBUG** statement, as shown in this example. The output from the program is included below, for reference. 

```spin2
' Floating Point Example Using Propeller Tool Debug

CON
  _clkfreq      = 10_000_000

PUB go()| radius, area

  radius := 6.2             ' 6.2 radius circle
  area := (PI *. (radius *. radius))
  debug(FDEC(area))
```

![](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/debug-float-1.jpg)

When the DEBUG command is used, the serial port is held by the DEBUG Output window and you will not be able to use Parallax Serial Terminal.

**Example #2: Propeller Tool for Windows Using Parallax Serial Terminal**

Parallax Serial Terminal may be used to display a floating-point number using a method in jm_fullduplexserial.spin2. If **X** is the number of digits you would like to display after the decimal point, multiply your floating-point value by **10.0^X** and then convert it to a fixed point for display using **%f** in a formatted print statement. Alternatively, the **dpdec()** method may also show the value right of the decimal point. 

The relevant lines of code are highlighted below (and note that the debug statements are removed).

```spin2
' Floating Point Example Using PST or ANSI Terminal

CON
  _clkfreq      = 10_000_000
  BR_TERM  = 230_400
  #0, T_PST, T_ANSI
  T_TYPE = T_PST

obj
  term   : "jm_fullduplexserial"
  ansi   : "jm_ansi"

PUB go()| i, radius, area

  term.tstart(BR_TERM)
  wait_for_terminal(true)

'' Area = PI*R*R example
  radius := 6.2             ' 6.2 radius circle
  area := (PI *. (radius *. radius))
  area := round(area *. 1000000.0)
  term.fstr1(string("Area = %.6fr"), area)

pub wait_for_terminal(clear)

'' Wait for terminal to be open and key pressed

  term.rxflush()
  term.rx()
  if (clear)
    clear_screen()

pub clear_screen()

  if (T_TYPE == T_PST)
    term.tx(term.CLS)
  else
    term.str(ansi.hide_cursor())
    term.str(ansi.home())
    term.str(ansi.cls())
```

![](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/debug-PST-600x947.jpg)

**Example #3: FlexProp and ANSI Terminal**

Eric Smith’s FlexProp may be used the same way as Propeller Tool, with the additional benefits of Mac and Linux. To use Terminal with FlexProp, change the T_TYPE to T_ANSI and compile. 

![](/qbi/Floating Point Math_ DEBUG And Terminal Display Example - Parallax_files/debug-FlexProp-600x1023.jpg)

To use the DEBUG commands in FlexProp, go to Options | BRK Debug. 

##### Parts Used

- [P2 Edge Module](https://www.parallax.com/product/p2-edge-module/)
- [P2 Edge Breadboard](https://www.parallax.com/product/p2-edge-module-breadboard/)

##### Source Code

- [Floating Point Example for PST and FlexProp Terminal](/qbi/downloads/floating_point_demo_pst-Archive-Date-2022.05.22-Time-14.18.zip)
- [DEBUG Example for Propeller Tool and FlexProp](/qbi/downloads/floating_point_demo-debug.spin2)

##### Programming Language

- [Spin 2](https://docs.google.com/document/d/16qVkmA6Co5fUNKJHF6pBfGfDupuRwDtf-wyieh_fbqw/)

##### Tools and Operating System

- [Propeller Tool for Windows](https://www.parallax.com/package/propeller-tool-software-for-windows-spin-assembly-2/)
- [FlexProp for Windows, Mac and Linux](https://www.patreon.com/totalspectrum)

##### Additional Resources

- [Graphical Debug Tools in Spin2](https://www.parallax.com/propeller-2-graphical-debug-tools-in-spin2/)

##### Document Author

- Ken Gracey

##### Source Code Author

- Ken Gracey, Jon McPhalen