# Yuji Zhang

### Tufts University Medford

I'm a Ph.D. student working on nonlinear optics. I use Matlab to process experimental data and, the more complicated thing is, perform numerical simulation of light propagation based on partial differential equations.

Professional Interests: nonlinear optics

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**Content Feed**

Question

display rescaled matrix as image: imagesc vs wcodemat

Hi I tried two ways to rescale a matrix and display as an image: imagesc and wcodemat. Worded well in Fig 1. But in figure 2:...

9 years ago | 0 answers | 0

### 0

answersnumber divided by vector

I think I figured out myself. Division is defined by multiplication. For any A, B, and C, A/B = C means A = B*C. Note ...

9 years ago | 0

Question

number divided by vector

Hi everyone~ I divided a number by a vector and forgot to use ./ Why it didn't report error and gave me some result? What's the...

9 years ago | 4 answers | 0

### 4

answersQuestion

is x' * x faster than x.^2 (x is a vector)

Hi~ Somebody recommended me to use x' * x. Is it faster than sum(x.^2) ? Any thoughts are appreciated. Thanks! [EDITED, s...

9 years ago | 2 answers | 1

### 2

answersQuestion

access values in dataset

hi In the results of lm = LinearModel.fit(x, y) there is lm.Coefficients containing the coefficient values. E.g., >...

9 years ago | 2 answers | 0

### 2

answersQuestion

what does c(:).' mean? c should be a vector

Hi I saw this in Matlab document: function obj = DocPolynom(c) % Construct a DocPolynom object using the coefficients...

9 years ago | 2 answers | 0

### 2

answersQuestion

waterfall appear to be out of box

Hi everyone, One waterfall plot appears that the curve are for outside the axis range. See this... Does anyone know how to fi...

10 years ago | 0 answers | 0

### 0

answersQuestion

how to see the script of build-in function?

Hi all~ I put "edit sum" in the command line. And I only saw the notes about it (begin with %). How can I see the script of t...

10 years ago | 1 answer | 0

### 1

answerQuestion

reverse of fnval: evaluate the variable for given value of function

Hi everyone~ See the picture. The blue dots are my data. I want to find out at what x values the function drop to -20 (red ci...

10 years ago | 1 answer | 0

### 1

answerQuestion

curve fitting: how to get the fitting curve?

Hi everyone~ I did some curve fitting using curve fitting toolbox. But I don't know how to get the fitting curve. Can somebo...

10 years ago | 1 answer | 0

### 1

answerQuestion

about axis ticks: how to set 10 ticks with 5 labels?

Hi everyone, I want the axis to have ticks at 1:1:10, and tick labels only at 2:2:10 Anybody know how to do this? I tri...

10 years ago | 1 answer | 0

### 1

answerQuestion

figures got chopped when saved using "print"

Hi everyone~ I plot some figures, and save them to .tif file using "print" But it often got chopped. I use the code ...

10 years ago | 0 answers | 0

### 0

answersQuestion

multiple fittings in comparison in curve fitting toolbox

Hi everyone~ I'm using the curve fitting toolbox, for curve fitting, of course. I couldn't figure out how to show multiple...

10 years ago | 0 answers | 0

### 0

answersQuestion

-v7.3 switch

Hi everyone~ I had problem saving a large variable (It's a cell. I think the problem is it's very large) The message is th...

10 years ago | 1 answer | 1

### 1

answerQuestion

loss of details using "print"

Hi everyone~ I was trying to plot some nice graphs. I tuned everything. It shows what I want in the Matlab plot window. But w...

10 years ago | 1 answer | 0

### 1

answerQuestion

pcolor - how to smooth

Hi everyone~ I'm plotting some contour map (x, y, z) If I use Origin, it does some nice smoothing. In Maltab, using ...

10 years ago | 3 answers | 0

### 3

answersQuestion

why definition of sine transform is not consistent with FFT?

<<https://lh4.googleusercontent.com/-QiXTlOnPnxE/UhRwYWPguoI/AAAAAAAAAx0/h2iASWeaI18/w1027-h432-no/dst.jpg>> See the picture....

10 years ago | 0 answers | 0

### 0

answersQuestion

the size of plot using "print"

Hi everyone~ I have a question about saving plot as pictures. I heard of the Oliver Woodford code but still want to check wi...

10 years ago | 0 answers | 0

### 0

answersQuestion

genvarname -> Index exceeds matrix dimensions.

Hi everyone~ I have a quite stupid question here. genvarname doesn't work here, like this: >> vname = genvarname ('aaa'...

10 years ago | 1 answer | 0

### 1

answerQuestion

manually run ode45 step by step - and impose filter to the half-way solution

Hi everybody~ I'm solving a ode: %% code 1 t = [tt1 tt2 tt3 ... tt100]; [t, y] = ode45(@equation, t, y1, optio...

10 years ago | 1 answer | 0

### 1

answerQuestion

how to create customized curve ( only know the shape )

<<https://lh5.googleusercontent.com/-carEAOQXYm4/UcA2uOb251I/AAAAAAAAArQ/gBZKnJAQ8_o/w356-h463-no/curve.jpg>> Hi everyone~ ...

10 years ago | 3 answers | 0

### 3

answersQuestion

about gradient and diff

The help of my matlab says: (in article "gradient -Gradient vector of scalar function") -If x is a scalar, gradient(f,x) = ...

10 years ago | 1 answer | 0

### 1

answerQuestion

doing derivative using diff(Y)/dT makes the vector shorter

Hi everybody, I'm doing derivative of a curve Y-T I think it's: T = linspace(-t, t, n); Y = somefuction; dT = T(2)-T(1...

10 years ago | 3 answers | 0

### 3

answersQuestion

syntax of handle: f = @(X)find(X);

Hi everyone~ I'm learning about use handle. The usual syntax is h = @FuncName But I also saw an example of f = @(X)find(X...

11 years ago | 2 answers | 0

### 2

answersQuestion

"find" function doesn't work

Hi~ I got a weird problem here. See the attached picture. "find" works for some values and doesn't for some others. It could a s...

12 years ago | 1 answer | 0