# Alan Stevens

**Statistics**

**MATLAB Answers**

**0** Questions

**1,184** Answers

RANK**54**

of 276,247

REPUTATION**3,140**

CONTRIBUTIONS

**0** Questions

**1,184** Answers

ANSWER ACCEPTANCE **
0.00%
**

VOTES RECEIVED**321**

RANK

of 18,594

REPUTATION**N/A**

AVERAGE RATING**0.00**

CONTRIBUTIONS**0** Files

DOWNLOADS **0**

ALL TIME DOWNLOADS**0**

RANK

of 125,970

CONTRIBUTIONS

**0** Problems

**0** Solutions

SCORE**0**

NUMBER OF BADGES**0**

CONTRIBUTIONS**0 Posts**

CONTRIBUTIONS**0** Public Channels

AVERAGE RATING

CONTRIBUTIONS**0** Highlights

AVERAGE NO. OF LIKES

**Content Feed**

Subscript indices must either be real positive integers or logicals always show up. what should i do?

Well, this works, but you might want to check the correctness or otherwise of your mode_shape calculations (there are a lot of z...

21 hours ago | 1

incorrect number or types of inputs or outputs for function 'int'

Replace your power calculation with power = (1/T_0) * trapz(t,y.^2); Edited - Walter is correct.

3 days ago | 0

Regula-falsi Method that keeps running

Brackets!! f = @(x) 2.^x - x.^2 - 2; % Function whose roots are desired xL = 4; xU = 5; % Initial guesses Tol = 1...

13 days ago | 0

| accepted

Trying to answer a math problem using newton's method but having problem in the function.

Matlab doesn't like implied multiplication (x ^ 2)z should be (x ^ 2)*z etc. Also, in Matlab log(x) is ln(x)

15 days ago | 0

| accepted

How to set multiple values of a threshold?

Here's one way: tolX1_4 = [1 1 1 1 1 -1 1 1 0 1 1 1 1 1 1 1 1 ...

15 days ago | 0

| accepted

Please help solve a system of differential equation

Here's a numerical approach: First manipulate the equations tspan = [0, 120]; ic = [80000, 0.001]; [t, xy] = ode45(@rate, ...

17 days ago | 0

how ode solver works

doc ode45 Go to the References section. The two references listed will supply you with all you need to know about the ode solv...

18 days ago | 0

Solve Differential Equation with initial conditions and function

Try modifying your if statement in Moment. Something like if x<a V =...; M = ...; elseif x>=a && x<L M = ... ...

18 days ago | 0

problem in creating function file using ode45

Are you looking for something like this? (I might have misinterpreted your equations!) O=1; a=pi/2; g=9.81; L=100; tspan ...

22 days ago | 0

how can eliminate negative data in erf function?

Should term2(i) = (sqrt(lemdaD)./(2.*e1(i))).*exp(-(v1(i).*sqrt_avgsnr - v2(i).* mu).^2./(2.*e1(i).^2)).*.... erf((e4(...

22 days ago | 0

| accepted

Why is my plot not showing for improved Euler method?

You need to keep track of each step. Your original simply overwrites the values of t and y at each step. dy=@(t,y) -(0.1/10^(1...

26 days ago | 1

Why I couldn't plot this graph f=(@(x,y) (x.^2)+(x*y)+(y.^2)<=68200.^2/3);

This will give you the outline (I've assumed you want 68200^(2/3) rather than 68200^2/3) f=@(x,y) x.^2+x.*y+y.^2-68200.^(2/3); ...

28 days ago | 0

I want to solve a simple "y=mx+c" with initial condition to find value of "m" and "c" but i am getting error by using following code. Any idea to tackle this kind of problem?

These are simple linear equations in m and c so set: X = [x(1) 1; x(2) 1]; Y = [y(1); y(2)]; and solve using X\Y to get m a...

29 days ago | 0

I have been trying to code a solar pv module for 1 diode model, the following is my code, can someone tell me the mistake ive made and the correction to it pls.

Like this? Note: I've made kref positive to avoid the I's being complex. This might be completely incorrect!! Pmpp = 50; ...

29 days ago | 1

| accepted

Reorganization of data in matrix

Like this? M = [1 1 0.270588872500870 1 1 0.191034400222846 1 1 0.316821350897659 1 1 0.391794699189989 1 2...

1 month ago | 0

LogLog Plot is Blank

Like this? (I've assumed you want log base 10 everywhere): %Paschen Curve Plotting for H2 p = 1.2; %Torr d = 20; %cm GamSE ...

1 month ago | 1

How to combine multiple numbers into 1 number?

Do you mean R1 = 2; R2 = 4; Zr1 = [0 0 0]; R = R1*10^4+R2*10^3+Zr1(1)*10^2+Zr1(2)*10+Zr1(3) Alternatively: R1 = 2; R2 = 4; Z...

1 month ago | 0

Runge Kutta Fourth order and Interpolation

Shouldn't f1 = @(z,r,ed,p11,m11) -(ed+p11)*z*m11.^3 *((r+1)./(((ed+p11)*(r.^2 +z.^2).^6) -(r/p11))) ./(2*pi*(r.^2 + z.^2)) ; ...

1 month ago | 0

Newton Raphson method for a system of non-linear equations?

Here's a simple example for you to follow: % Functions f = @(x,y) x^2 + y - 5.94; % i.e. the equation is x^2+y=5.94 g = @(x,...

2 months ago | 0

| accepted

No feasible solution in optimisation in linprog

I don't know if this will fix your problem, but I think the first number in the second row of A1 should be 8 not 2.

2 months ago | 0

Simple relaxation method Matlab

For the simple relaxation technique to work the A matrix needs to be diagonally dominant. Your A is not diagonally dominant - s...

2 months ago | 0

| accepted

Solve a system of 3 second order equations

Write your equations as 6 first order equations like so: where I've assumed you have pre-defined omegaout and thetaout as fun...

2 months ago | 0

Unable to solve nonlinear equation using fsolve as the message shows No solution found

fminsearch makes a reasonable attempt: F1 = @(a,b) -9.135789053E+00-log(a)+166.2509975*a+5.84074229*b+... -166.2509975*a^2...

2 months ago | 2

How to solve and plot this set of differential equations?

If rho starts at 0, then drho/dtheta will be zero and rho will not change from zero according to your first ode. If rho and drh...

2 months ago | 0

How can I add two differential equations to the system in a given time interval?

Like this? (though I'm not sure I've interpreted which constants apply during which interval correctly!) Tspan = 0:30; C0 =...

2 months ago | 1

| accepted

How do I plot Rosette-like diagram in this case?

Something like this? data=[10 10 30 100; 20 50 70 150; 30 45 60 120]; theta0 = deg2rad(data(:,2)); thetaf = deg2r...

2 months ago | 1

| accepted

Iteration of multiple nonlinear functions

Here's a quick and dirty way. I'll leave you to modify the following to record all the temperatures at every step. %Given valu...

2 months ago | 0

using num2str for subplot titles

Try title(['Q1S', num2str(k)]) i.e. enclose the two terms within square brackets.

2 months ago | 0

| accepted

control and simulation of petroleum distillation column

The following works, but probably doesn't contain all the right data or equations! % CALCULATE MATERIAL BALANCES FOR THE DISTIL...

2 months ago | 0

| accepted