MATLAB Answers

Why is my function not working?

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Eric Hofmann
Eric Hofmann on 4 Sep 2021
Edited: per isakson on 4 Sep 2021
%clear program all together
clear
clc
%create function for velocity(m/s)
function U = (n,S,H,B);
U = sqrt(S)*((B*H/(B+2*H))^(2/3))/n;
T = zeros(6,5);
for i = (1:5)
T(2,1)=0.036;T(2,2)=0.0001;T(2,3)=10;T(2,4)=2;T(2,5)=velocity(.036,.0001,10,2);
T(3,1)=0.020;T(3,2)=0.0002;T(3,3)=8;T(3,4)=1;T(3,5)=velocity(.020,.0002,8,1);
T(4,1)=0.015;T(4,2)=0.0012;T(4,3)=20;T(4,4)=1.5;T(4,5)=velocity(.015,.0012,20,1.5);
T(5,1)=0.030;T(5,2)=0.0007;T(5,3)=25;T(5,4)=3;T(5,5)=velocity(.030,.0007,25,3);
T(6,1)=0.022;T(6,2)=0.0003;T(6,3)=15;T(6,4)=2.6;T(6,5)=velocity(.022,.0003,15,2.6);
end

Answers (3)

Yongjian Feng
Yongjian Feng on 4 Sep 2021
You meant:
function U = velocity(n,S,H,B)
U = sqrt(S)*((B*H/(B+2*H))^(2/3))/n;
end
  2 Comments
Yongjian Feng
Yongjian Feng on 4 Sep 2021
Save your function into a velocity.m file, and run the test from matlab command line window.
  1. Your velocity.m has the function:
function U = velocity(n,S,H,B)
U = sqrt(S)*((B*H/(B+2*H))^(2/3))/n;
end
2. Then run the test from the command line window.
T = zeros(6,5);
for i = (1:5)
T(2,1)=0.036;T(2,2)=0.0001;T(2,3)=10;T(2,4)=2;T(2,5)=velocity(.036,.0001,10,2);
T(3,1)=0.020;T(3,2)=0.0002;T(3,3)=8;T(3,4)=1;T(3,5)=velocity(.020,.0002,8,1);
T(4,1)=0.015;T(4,2)=0.0012;T(4,3)=20;T(4,4)=1.5;T(4,5)=velocity(.015,.0012,20,1.5);
T(5,1)=0.030;T(5,2)=0.0007;T(5,3)=25;T(5,4)=3;T(5,5)=velocity(.030,.0007,25,3);
T(6,1)=0.022;T(6,2)=0.0003;T(6,3)=15;T(6,4)=2.6;T(6,5)=velocity(.022,.0003,15,2.6);
end
T

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per isakson
per isakson on 4 Sep 2021
Edited: per isakson on 4 Sep 2021
The function must be at the end of the m-file. It's a local file in a script. (Or you can have the script and the function in two separate files. See Scripts vs. Functions.)
%%
T = zeros(6,5);
for i = (1:5)
T(2,1)=0.036;T(2,2)=0.0001;T(2,3)=10;T(2,4)=2;T(2,5)=velocity(.036,.0001,10,2);
T(3,1)=0.020;T(3,2)=0.0002;T(3,3)=8;T(3,4)=1;T(3,5)=velocity(.020,.0002,8,1);
T(4,1)=0.015;T(4,2)=0.0012;T(4,3)=20;T(4,4)=1.5;T(4,5)=velocity(.015,.0012,20,1.5);
T(5,1)=0.030;T(5,2)=0.0007;T(5,3)=25;T(5,4)=3;T(5,5)=velocity(.030,.0007,25,3);
T(6,1)=0.022;T(6,2)=0.0003;T(6,3)=15;T(6,4)=2.6;T(6,5)=velocity(.022,.0003,15,2.6);
end
disp(T)
0 0 0 0 0 0.0360 0.0001 10.0000 2.0000 0.2607 0.0200 0.0002 8.0000 1.0000 0.4278 0.0150 0.0012 20.0000 1.5000 1.8602 0.0300 0.0007 25.0000 3.0000 1.1116 0.0220 0.0003 15.0000 2.6000 0.8872
%% create function for velocity(m/s)
function U = velocity(n,S,H,B);
U = sqrt(S)*((B*H/(B+2*H))^(2/3))/n;
end

Image Analyst
Image Analyst on 4 Sep 2021
Try this:
% Demo by Image Analyst
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 25;
fprintf('Beginning to run %s.m ...\n', mfilename);
% Call the function
U = velocity(4,37,73,42);
fprintf('Done running %s.m\n', mfilename);
T = zeros(6,5);
for i = (1:5)
T(2,1)=0.036;
T(2,2)=0.0001;
T(2,3)=10;
T(2,4)=2;
T(2,5)=velocity(.036,.0001,10,2);
T(3,1)=0.020;
T(3,2)=0.0002;
T(3,3)=8;
T(3,4)=1;
T(3,5)=velocity(.020,.0002,8,1);
T(4,1)=0.015;
T(4,2)=0.0012;
T(4,3)=20;
T(4,4)=1.5;
T(4,5)=velocity(.015,.0012,20,1.5);
T(5,1)=0.030;
T(5,2)=0.0007;
T(5,3)=25;
T(5,4)=3;
T(5,5)=velocity(.030,.0007,25,3);
T(6,1)=0.022;
T(6,2)=0.0003;
T(6,3)=15;
T(6,4)=2.6;
T(6,5)=velocity(.022,.0003,15,2.6);
end
% Create function for velocity(m/s)
function U = velocity(n,S,H,B)
U = sqrt(S)*((B*H/(B+2*H))^(2/3))/n;
end

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