Answered

Eigenvectors are not orthogonal for some skew-symmetric matrices, why?

Your matrix A is _"defective"_ , meaning that its eigenvalues are not all distinct. In fact, it has only three distinct eigenva...

Eigenvectors are not orthogonal for some skew-symmetric matrices, why?

Your matrix A is _"defective"_ , meaning that its eigenvalues are not all distinct. In fact, it has only three distinct eigenva...

6 months ago | 1

| accepted

Answered

Sum of highest length of consecutive lowest values from a array.

L = min(A); f = find(diff([false,A==L,false])~=0); h = L*max(f(2:2:end)-f(1:2:end-1)); h is the highest sum of consec...

Sum of highest length of consecutive lowest values from a array.

L = min(A); f = find(diff([false,A==L,false])~=0); h = L*max(f(2:2:end)-f(1:2:end-1)); h is the highest sum of consec...

12 months ago | 0

Answered

What condition to use for checking whether at least a single negative element in a array?

Use the 'any' logical function. if any(A.*B<0) If you are dealing with an array, C, of more than one dimension, do this:...

What condition to use for checking whether at least a single negative element in a array?

Use the 'any' logical function. if any(A.*B<0) If you are dealing with an array, C, of more than one dimension, do this:...

12 months ago | 0

| accepted

Answered

How to Make a Matrix Diagonal with Matlab?

Call on Matlab's 'svd' function. Read about it at: https://www.mathworks.com/help/matlab/ref/svd.html or possible you n...

How to Make a Matrix Diagonal with Matlab?

Call on Matlab's 'svd' function. Read about it at: https://www.mathworks.com/help/matlab/ref/svd.html or possible you n...

12 months ago | 0

Answered

Finding if a vector is a subset

The following should be faster: m = size(a,2); n = size(b,2); for k = 1:n-m+1 s = all(a==b(k:k+m-1)); if s,...

Finding if a vector is a subset

The following should be faster: m = size(a,2); n = size(b,2); for k = 1:n-m+1 s = all(a==b(k:k+m-1)); if s,...

12 months ago | 0

| accepted

Answered

How to plot level curves of f(x,y) = 2x^2 + 5y^2. f(x,y) = c for c = 1,2,3,4,5,6

Your "level" curves are all ellipses and can most easily be generated by: t = linspace(0,2*pi); x = sqrt(c/2)*cos(t); ...

How to plot level curves of f(x,y) = 2x^2 + 5y^2. f(x,y) = c for c = 1,2,3,4,5,6

Your "level" curves are all ellipses and can most easily be generated by: t = linspace(0,2*pi); x = sqrt(c/2)*cos(t); ...

12 months ago | 0

Answered

how to make a function (named pcc ) that solves the cartesian product of 2 strings A(with n elements) and B(with m elements)?

Assume A and B are row strings. C = [reshape(repmat(A,length(B),1),[],1),repmat(B(:),length(A),1)]; The two-element rows...

how to make a function (named pcc ) that solves the cartesian product of 2 strings A(with n elements) and B(with m elements)?

Assume A and B are row strings. C = [reshape(repmat(A,length(B),1),[],1),repmat(B(:),length(A),1)]; The two-element rows...

12 months ago | 0

Answered

how to create function half adder in matlab

If the input bits are numeric scalars or logical values, b1 and b2, then the sum bit, 's', would be: s = b1 xor b2; or e...

how to create function half adder in matlab

If the input bits are numeric scalars or logical values, b1 and b2, then the sum bit, 's', would be: s = b1 xor b2; or e...

12 months ago | 0

| accepted

Answered

Using nested loops, write a Matlab program that goes through all elements of a matrix (2D array) and replaces every element that is either a multiple of 5 or 7 with -1.

Your test on a number x from your array can be: if round(x/5)==x/5 | round(x/7)==x/7 (Doing fprintf('-1') just prints ou...

Using nested loops, write a Matlab program that goes through all elements of a matrix (2D array) and replaces every element that is either a multiple of 5 or 7 with -1.

Your test on a number x from your array can be: if round(x/5)==x/5 | round(x/7)==x/7 (Doing fprintf('-1') just prints ou...

12 months ago | 0

Answered

What is the output?

The vector x has only three elements, [0,.3,.6], so the 'for' instruction reads: for n = 4:2 Therefore the loop will not...

What is the output?

The vector x has only three elements, [0,.3,.6], so the 'for' instruction reads: for n = 4:2 Therefore the loop will not...

12 months ago | 0

Answered

Please help me convert equation to matlab code.

N = 100; % <-- Choose some large number s = x; for n = 2*N-1:-2:1 s = x - s*x^2/((n+2)*(n+1)); end (I t...

Please help me convert equation to matlab code.

N = 100; % <-- Choose some large number s = x; for n = 2*N-1:-2:1 s = x - s*x^2/((n+2)*(n+1)); end (I t...

12 months ago | 0

Answered

Why am I getting Inf in my matrix

It is easily possible for two finite nonzero numbers to have a quotient so large that Matlab must give 'inf' as its value. For ...

Why am I getting Inf in my matrix

It is easily possible for two finite nonzero numbers to have a quotient so large that Matlab must give 'inf' as its value. For ...

12 months ago | 1

| accepted

Answered

Multiply a column by a number

Let Ar be the name of the array. Ar(:,6) = 4*Ar(:,6); What could be simpler? Since 4 is a scalar, it is automatically a...

Multiply a column by a number

Let Ar be the name of the array. Ar(:,6) = 4*Ar(:,6); What could be simpler? Since 4 is a scalar, it is automatically a...

12 months ago | 0

Answered

how to use nested for loop by grabbing one column and subtracting another column.

Your n value will be 1478, but in z(i,j+1) you have allowed the j+1 index to get as large as 1479 because you have "for j=1:1:n"...

how to use nested for loop by grabbing one column and subtracting another column.

Your n value will be 1478, but in z(i,j+1) you have allowed the j+1 index to get as large as 1479 because you have "for j=1:1:n"...

12 months ago | 0

Answered

Why does y come out as one number?

The scalar result is caused by the use of matrix division rather than element-by-element division. Replace '/' by './'. Simila...

Why does y come out as one number?

The scalar result is caused by the use of matrix division rather than element-by-element division. Replace '/' by './'. Simila...

12 months ago | 0

Answered

Lagrange Interpolation code error

The message is caused by your not defining or properly entering the value of vector 'xi'.

Lagrange Interpolation code error

The message is caused by your not defining or properly entering the value of vector 'xi'.

12 months ago | 0

Answered

Trapezoidal rule to find total work?

I would think your code should be this: work = 0; for k = 2:length(t) work = work + (F(k)+F(k-1))/2*(v(k-1)+v(k))/2...

Trapezoidal rule to find total work?

I would think your code should be this: work = 0; for k = 2:length(t) work = work + (F(k)+F(k-1))/2*(v(k-1)+v(k))/2...

12 months ago | 0

| accepted

Answered

How to do polynomial differentiation

Let P be the usual Matlab row vector of coefficients of a polynomial. Then, (as we all learned in calculus,) the corresponding ...

How to do polynomial differentiation

Let P be the usual Matlab row vector of coefficients of a polynomial. Then, (as we all learned in calculus,) the corresponding ...

12 months ago | 1

| accepted

Answered

convert two column matrices into one column matrix

In the example you gave do this: C = zeros(9,1); C(1:2:end) = A; C(2:2:end) = B; For a general answer you need to ...

convert two column matrices into one column matrix

In the example you gave do this: C = zeros(9,1); C(1:2:end) = A; C(2:2:end) = B; For a general answer you need to ...

12 months ago | 0

Answered

Does 'i' after value stand for 'index', and if so why does it appear as part of the answer?

The 'i' in your result indicates a complex answer. I assume you are familiar with complex numbers. The 'i' represents the squa...

Does 'i' after value stand for 'index', and if so why does it appear as part of the answer?

The 'i' in your result indicates a complex answer. I assume you are familiar with complex numbers. The 'i' represents the squa...

12 months ago | 1

| accepted

Answered

Representing base 4 numbers as "random walks"

The Matlab function 'dec2base' can be used to covert integers to character strings involving the characters '0', '1', '2', and '...

Representing base 4 numbers as "random walks"

The Matlab function 'dec2base' can be used to covert integers to character strings involving the characters '0', '1', '2', and '...

1 year ago | 0

Answered

How to generate a joint probability matrix from a data matrix

Call the data matrix D. Then the two columns of D(:,2:3) are X and Y. XY = sortrows(D(:,2:3)); F = find( [true,any(XY(1...

How to generate a joint probability matrix from a data matrix

Call the data matrix D. Then the two columns of D(:,2:3) are X and Y. XY = sortrows(D(:,2:3)); F = find( [true,any(XY(1...

1 year ago | 0

Answered

How can I write a program that indicates a number if it is integer or not?

If n is your number, then round(n)==n is true if and only if n is an integer

How can I write a program that indicates a number if it is integer or not?

If n is your number, then round(n)==n is true if and only if n is an integer

1 year ago | 0

Answered

where can i use round function to make the function perfect

I would suggest initially multiplying both 'tendered' and 'price' by 100 and using 'round' on the result: tendered = round(...

where can i use round function to make the function perfect

I would suggest initially multiplying both 'tendered' and 'price' by 100 and using 'round' on the result: tendered = round(...

1 year ago | 0

| accepted

Answered

if a & b

You can't use the "short circuit" forms of logical operations for operands other than scalars. The double symbol '&&' is the sh...

if a & b

You can't use the "short circuit" forms of logical operations for operands other than scalars. The double symbol '&&' is the sh...

1 year ago | 1

Answered

How do I use an matrix of indices to reference values in another matrix without using a loop?

[a,b,c] = size(alltemps); % tempindex must be 1 x b x c savedtemp = reshape(alltemps(reshape(tempindex,1,[])+(0:a:a*(b*c-1...

How do I use an matrix of indices to reference values in another matrix without using a loop?

[a,b,c] = size(alltemps); % tempindex must be 1 x b x c savedtemp = reshape(alltemps(reshape(tempindex,1,[])+(0:a:a*(b*c-1...

1 year ago | 0

| accepted

Answered

Solving a system of integral equations numerically

@Lewis: I noticed that the integrands in both of your integrals become infinite at the upper limit of integration, and this can ...

Solving a system of integral equations numerically

@Lewis: I noticed that the integrands in both of your integrals become infinite at the upper limit of integration, and this can ...

1 year ago | 0

Answered

Solving a system of integral equations numerically

This is a problem you can solve using Matlab's 'fsolve' function. The fact that your objective function requires two numerical ...

Solving a system of integral equations numerically

This is a problem you can solve using Matlab's 'fsolve' function. The fact that your objective function requires two numerical ...

1 year ago | 0

Answered

How to plot a circle centered on a line and passing through a point?

There are infinitely many ways a circle can be centered on a line and pass through a given point, except for the case when a lin...

How to plot a circle centered on a line and passing through a point?

There are infinitely many ways a circle can be centered on a line and pass through a given point, except for the case when a lin...

1 year ago | 0

Answered

Matrix column subtraction problem

C = zeros(5,2*3); for p = 1:2 for q = 1:3 C(:,3*p+q-3) = A(:,p)-B(:,q); end end Or this: C = re...

Matrix column subtraction problem

C = zeros(5,2*3); for p = 1:2 for q = 1:3 C(:,3*p+q-3) = A(:,p)-B(:,q); end end Or this: C = re...

1 year ago | 0

| accepted