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# David Hill

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1,660 total contributions since 2017

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Check Digit - 02
Given a list of ISBN's, check whether they're valid or not. Prev Prob - <https://www.mathworks.com/matlabcentral/cody/problem...

4 hours ago

how can I set axis's tick or scale like photo.. help plz,,
CD = @(Re) 24./Re+(2.6*Re/5)./(1+(Re/5).^1.52)+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/10^6)./(1+Re/10^6); ...

1 day ago | 1

How can i create a code which accept the 'peaks' of a quadrilateral and then give me the area of it?(without polyarea)
I would use the polyshape function or polyarea function pgon=polyshape([0 2 1 2],[0 2 0 -2]); a=area(pgon); plot(pgon); If y...

1 day ago | 0

Solved

Inscribed circle in a triangle
A circle of radius r is inscribed in a triangle. In the figure, Ac=x and Bc=y. values of x & y are given. Find the ar...

2 days ago

Solved

Spiral Out - 02
An array is given. Convert it into a spiral matrix. For example, a=1:27; out=[21 22 23 24 25 26 20 ...

2 days ago

Solved

Spiral Out - 01
Create a spiral matrix ( clock-wise direction ) of size n. Try to do that without using the built-in function.

2 days ago

"Matrix dimensions must agree" and "error using /"
% Find the temperature using Van der Waal's equation T_VW_b= (P+(((n^2)*a)./(V.^2))).*(V-n*b)/(n*R);%since V is an array, need ...

2 days ago | 0

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Algorithm to scan the total elements in a matrix randomly
A=[1 2 3;4 5 6]; a=A<=A(randi(numel(A)));

2 days ago | 0

Solved

Relative ratio of "1" in binary number
Input(n) is positive integer number Output(r) is (number of "1" in binary input) / (number of bits). Example: * n=0; r=...

4 days ago

How do i split an image into 8x8 blocks using a function?
I assume you have the image processing toolbox. Look at Neighborhood and Block Processing. blockproc() col2im()

4 days ago | 0

using linear interpolation to find coefficients
Make sure your matrix agrees with the meshgrid generated or change it to match. [d,a]=meshgrid(AerodynamicData.Cm.BodyFlap.deBF...

4 days ago | 1

using MATLAB determine the unit vector normal to 𝐒=𝐱𝟐+𝐲𝟐−𝐳 at point P(1,3,0).
syms x y z s = x^2+y^2-z; n(x,y,z) = gradient(s, [x, y, z]); a = eval(n(1,3,0)/norm(n(1,3,0)));

5 days ago | 0

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How can i solve this?
a=mean(abs(A),'all'); s=sum(A>a,'all');

5 days ago | 0

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Why does MATLAB do this?
floating point error isequal(round(transpose(inv(A)),15),round(inv(transpose(A)),15));

5 days ago | 1

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calling subfunctions multiple times
function problem5(n) k=0:20;%method1 gets very slow causing the function to take a few minutes for low values of n=3 for i=k ...

5 days ago | 1

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How do I correctly enter the function f(x,y)=sin((pi/2)*(x+y))?
f=@(x,y)sin(pi/2*(x+y)); [X,Y]=meshgrid(-1:.2:1);%not sure what step size you are using a=interp2(X,Y,f(X,Y),1/3,1/3);

5 days ago | 0

Picking the right combination from the arrays
Not sure how you are getting your data. Generally, you would not want to use so many variables but rather index into a single va...

5 days ago | 0

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How can I convert this cell array into a matrix?
reshape(cell2mat(C),60,[])';

5 days ago | 0

Splitting up arrays in for loops
n=[0,find(diff(M(:,3))>1),size(M,1)]; for k=1:length(n)-1 m{k}=M(n(k)+1:n(k+1),:); end

5 days ago | 0

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Submitted

Secure Off-line Email Encryption GUI
Send and receive off-line encrypted emails using public-key cryptography and Advanced Encryption Standard (AES).

Differentiation and integration of functions
syms x; y=(11*x+1)/sqrt(x^2+22); dy=diff(y); ddy=diff(dy); for x=1:3 Dy(x)=double(subs(dy)); DDy(x)=double(subs(dd...

11 days ago | 0

How to get the matrix when I need a logic matrix
QQQQ=AAAA.*y;

11 days ago | 0

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Interpolation between intersecting curves
f=fit(x1',y1','poly5'); g=fit(x2',y2','poly5'); x=min(x2):.01:max(x2); h=1/4.5*(g(x)-f(x))+f(x);%only good for minimum x-rang...

13 days ago | 0

how to write the expression ((pi*epsilon)/ln((D-r)/r)) in matlab?
Are all the variables arrays of equal size? If so, then you need the element-wise operator. c = (pi*epsilon)./log((D-r)./r);

14 days ago | 0

Trapezodial Method using while loop
f=@(x) sin(x); tol=1e-6; x=linspace(0,pi,2); A=sum(movsum(f(x),2,'Endpoints','discard')/2.*diff(x)); n=2; while abs(2-A)>=t...

14 days ago | 0

how to reshape the matrix
m =[0 0 1 0 0 1 0 0 1 1 1 1 0 1 1 1 0 1 1 1 1]; a=reshape(m,3,[])';

15 days ago | 1

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Caesar cryptic function problem.
Assuming c is a double array function coded = caesar(c,n) coded=char(mod(c-32+n,95)+32); end

15 days ago | 0

How to compare two matrices, row by matrix using the GPU
Not sure if something like this would work for you. arrayfun(@(x)ismember(a,b(x,:)),1:size(b,1),'UniformOutput',false);

15 days ago | 0

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Vector of n elements
a=1:n; A=a.*(a+1)/2;

15 days ago | 0