Syntax of semilogx, semilogy, loglog

Hi,

I just realized that the following syntaxes are not valid

semilogx(X1,Y1,LineSpec,'PropertyName',PropertyValue)

semilogy(X1,Y1,LineSpec,'PropertyName',PropertyValue)

loglog(X1,Y1,LineSpec,'PropertyName',PropertyValue)

whereas

plot(X1,Y1,LineSpec,'PropertyName',PropertyValue)

is valid. Shouldn't this be fixed for consistency?

Answer 1

[Wayne King]

Hi Nicolas, Can you give an example?

    x = logspace(-1,2);
    loglog(x,exp(x),'-s','linewidth',2)

    figure;
    x = 0:0.1:10;
    semilogx(10.^x,x,'r--','linewidth',2)

[Nicolas]

My mistake, sorry. Got an error due to another bug and thought its due to loglog, since the above syntax is not documented.

[Wayne King]

Glad to hear it's working. Just out of curiousity, which version of MATLAB are you using that the above is not documented?

I see this documented for loglog all the way back to at least 2005.

[Nicolas]

I am using using R2011a. I was referring to the help entry of loglog. There it sais:

Syntax

loglog(Y)

loglog(X1,Y1,...)

loglog(X1,Y1,LineSpec,...)

loglog(...,'PropertyName',PropertyValue,...)

h = loglog(...)

[Nicolas]

On the other hand for plot it sais:

Syntax

plot(Y)

plot(X1,Y1,...,Xn,Yn)

plot(X1,Y1,LineSpec,...,Xn,Yn,LineSpec)

plot(X1,Y1,LineSpec,'PropertyName',PropertyValue)

plot(axes_handle,X1,Y1,LineSpec,'PropertyName',PropertyValue)

h = plot(X1,Y1,LineSpec,'PropertyName',PropertyValue)

Guess I wasn't interpreting the ... properly.

[Wayne King]

Right:

loglog(X1,Y1,LineSpec,....)

means:

x = logspace(-1,2);

loglog(x,exp(x),'-or')

or some other valid linespec (the 'or' is a linespec)

loglog(...,'PropertyName',PropertyValue,...)

means:

loglog(x,exp(x),'linewidth',2,'LineStyle','-.');

or some valid 'PropertyName',PropertyValue combination.

Glad it's working!

Answer 2

[UJJWAL]

Things are working ok... There is no inconsistency or I was not able to understand you.. Please check the following code and rephrase the question so that I would understand better :-

clc
clear all
t= 0:0.001:2;
plot(t,exp(t),'--.r','LineWidth',2);
figure(2);
semilogx(t,exp(t),'*k','LineWidth',2);
figure(3);
semilogy(t,exp(t),'-.b','LineWidth',2);
figure(4);
loglog(t,exp(t),'--y','LineWidth',2);

Answer 3

[Khaleel UR Rehman Khan]

If suppose we have to make the linewidth=3,

loglog(x,y,'linewidth',3) is wrong

the right syntax is

loglog(x,y,"Linewidth",3)

[Steven Lord]

loglog accepts the name of a name-value pair argument as a char vector or as a string perfectly fine when I tried it in release R2020a. Can you clarify why you believe the syntax with the name specified as a char vector is wrong? If you're seeing an error can you show all of the error message (all the text displayed in red?)

x = 1:10;
y = x.^2;
figure
loglog(x, y, 'linewidth', 3)

figure
loglog(x, y, "linewidth", 3)