Body-Mass Index

Computes body-mass index and plots bmi versus weight

Description

This function computes a person's body-mass index, or BMI, given his/her current weight in pounds and height in inches. The function also plots BMI versus weight for a range of weights specified by wRange.

Note that although the inputs are in U.S. conventional units of measure (so that it is convenient for use in the United States), the resulting BMI value is measured, by definition, in SI units.

To modify the code to use SI units for the input arguments, simply replace the line

      useSIunits = false;

with the line

      useSIunits = true;

and save the code. Then, when calling the function from the MATLAB, use kilograms for weight and meters for height, and the result should be correct. Note that the function will automatically change the units of measure in the title and the labels for each axis.

The author makes no claim as to the validity or usefulness of BMI as a measure of overall health or wellness. There are many resources available on the web and in the literature that describe BMI, what it means, and how to interpret the results.

Syntax:

    b = bmi(height,weight);

    b = bmi(height,weight,wRange);

Example:

    height = 68; % inches
    weight = 174; % pounds
    b = bmi(height,weight,[ 150 210 ]);

• MATLAB release: MATLAB 7.5 (R2007b)

[John D'Errico]

I'll admit I'm not entirely sure what purpose this serves as a Matlab utility. Since it seems to be of mainly educational value, why not add some links to more information about BMI? Perhaps these are a start:

http://www.cdc.gov/nccdphp/dnpa/bmi/

http://www.cardiometabolic-risk.org/

While I won't get into the questions of whether BMI is an accurate indicator of health, nor will I get into the issue of mono-numerosis, BMI surely is one indicator of health. So the author might have added some indication of what a reasonable BMI should be. Otherwise, its just a random number. The plot might have been done so that the line varies in color, scaled so that good BMI numbers would be green, turning to red at the high end.

The help itself for bmi.m is good. Its readable and concise, defining the inputs and outputs. I'm not terribly sure why the units on the inputs are in pounds and inches, yet the returned BMI has SI units. Tradition?

I found an H1 line, but no error checking on the arguments. OTOH, the arguments are pretty simple, so I'll excuse that lack. The code is pretty simple, so nothing to go wrong, and I did find internal comments before many lines.

Now, if I can only figure out how to be nine feet tall, I'll have a perfect BMI myself. ;-)