Question

by using matlab

linreg() function file given below

On average, the surface area A of human beings is related to weight W and height H. Measurements of several individuals of height 180cm are provided below. It is believed that the following data can be modelled using an exponential equation A = aeBW W (kg) 70 2.1 75 2.12 77 2.15 80 2.20 82 2.22 84 2.23 87 2.26 90 2.30 A (m2) A. Show by hand with pen and paper the linearisation of this nonlinear model. You do not need to perform any calculations, only the linearization of the model. You will need to present this work for marking. B. Plot the data set as blue cirlces. C. Use the linreg() function you've created to calculate the constants a, ß and r?. Use fprintf to print these values. D. Use the polyfit function in MATLAB to calculate a and B, and then determine the r of the fit. Use fprintf to print these values and compare your answers with Part C. E. Plot the nonlinear function as a red dashed line on the figure produced in part B, using x as a vector from 0 to 100 with increments of 1. Is this model appropriate?

Answer 1

`Hey,

Note: If you have any queries related the answer please do comment. I would be very happy to resolve all your queries.

Please note you should have linreg function in your directory saved as linreg.m to run this program

clc
clear all
close all
format long
W=[70,75,77,80,82,84,87,90];
A=[2.1,2.12,2.15,2.2,2.22,2.23,2.26,2.3];
plot(W,A,'ob');
[a0,a1,r2]=linreg(W,log(A));
alpha=exp(a0);
beta=a1;
fprintf('alpha using linreg is %f\n',alpha);
fprintf('beta using linreg is %f\n',beta);
fprintf('r2 using linreg is %f\n',r2);
C=polyfit(W,log(A),1);
a0=C(2);
a1=C(1);
alpha=exp(a0);
beta=a1;
f=@(x) alpha*exp(beta*x);
SSR=sum((A-f(W)).^2);
SST=sum((A-mean(A)).^2);
r2=1-SSR/SST;
fprintf('alpha using polyfit is %f\n',alpha);
fprintf('beta using polyfit is %f\n',beta);
fprintf('r2 using polyfit is %f\n',r2);
x=0:100;
y=f(x);
hold on;
plot(x,y,'--r');

MATLAB R2020a - academic use х HOME PLOTS APPS EDITOR PUBLISH VIEW CE ? Search Documentation Sign In ох A La Find Files Insert fx IS BV Run Section Compare Go To Comment % 3% New Open Save Breakpoints Run Run and Advance Run and A Print Find Indent Advance Time FILE NAVIGATE EDIT BREAKPOINTS RUN C: Users ► PRADEEP KALRA Documents ► MATLAB Current Folder Editor - C:\Users\PRADEEP KALRA\Documents\MATLAB\saveee.m Name A saveee.m X + T6 - al 1) + codegen convertFinal 17 - alpha=exp (ao) directory1 18 - beta=al; example 19 - f=@(x) alpha exp (beta*x); first 20 - SSR=sum ((A-f(W)).^2); googleLinks 21 - SST=sum ((A-mean (A)).^2); mathlab 22 - r2=1-SSR/SST; mynewdir 23 - fprintf('alpha using polyfit is f\n', alpha); n 24 - fprintf('beta using polyfit is f\n', beta); New folder 25 - fprintf('r2 using polyfit is {f\n',r2); questions old 26 - x=0:100; simple_gui2 27 - y=f(x); 1.png 28 - hold on; 2.png 29 - plot (x,y,'--r'); 3.pna 30 questions_old (Folder) Command Window Workspace alpha using polyfit is 1.494462 Name- Value beta using polyfit is 0.004777 ША [2.1000, 2.1200,2.1500,... r2 using polyfit is 0.977039 a0 0.4018 fx >> a1 0.0048 alpha 1.4945 beta 0.0048 HC [0.0048,0.4018] f @(x)alpha*exp(beta*x) r2 0.9770 HSSR 7.7495e-04 + 00 UTF-8 script Ln 30 Col 1 Type here to search TU A 09 ENG IN 3:41 PM 05/18/20

Kindly revert for any queries

Thanks.