m file that calls function nraizes(a) from another m file.
clear functions;
clc;
x = input('Insert value for a? ') ;
% call to nraizes()
w = nraizes(x)
clear functions;
nraizes.m file with nraizes() function:
printf("\n\n");
printf("nraizes por André Castro - UAB 901396");
printf("\n");
printf("Usar na próxima prompt: nraizes(valor numérico)");
printf("\n");
function n = nraizes(a)
% limpar a memoria de todas as vars e funções
clear functions;
clc;
% intervalo para x
x = 0:.1:25;
% ambas as funções h(x) e g(x)
h = #(x) cos(x);
g = #(x) exp(a*x)-1;
% traçar linha na origem das abcissas
or = x;
or(:) = 0;
% gráfico
plot(x, [h(x);g(x);or]);
axis([0, 25, -1, 1])
title("h(x),g(x)");
grid on;
printf("Fim do Script");
printf("\n");
% limpar a memoria de todas as vars e funções
clear functions;
endfunction
It always throws the following error:
warning: function 'nraizes' defined within script file '/Users/andrecastro/0_Thawed/1_UAB/1 UCS_INFORMATICA/Computacao Numerica/0 2015-2016_CN/1 Algoritmos_Octave/nraizes.m'
error: invalid use of script /Users/andrecastro/0_Thawed/1_UAB/1 UCS_INFORMATICA/Computacao Numerica/0 2015-2016_CN/1 Algoritmos_Octave/nraizes.m in index expression
error: called from:
error: /Users/andrecastro/0_Thawed/1_UAB/1 UCS_INFORMATICA/Computacao Numerica/0 2015-2016_CN/1 Algoritmos_Octave/script.m at line 19, column 7
I don't undestand why. Both .m files are in same path.
You have nraizes defined in a file with the same name as the function. You should not do it because now you have both a script and a function, both named nraizes which makes things confusing.
This is what the first warning means:
warning: function 'nraizes' defined within script file '[...]/nraizes.m'
It is warning that the function is on a script with the same name.
You can do it (it's only a warning) but you shouldn't. If you want to do it, you will need to first source the nraizes script and only after that will you have the function available:
nraizes; # source nraizes script
w = nraizes (x); # call nraizes function
That is why you got an error
error: invalid use of script [...]nraizes.m in index expression
because you tried to call a function (or index a variable -- remember that the function is not defined yet so Octave does not know) that does not exist.
However, the printf statements at the top of nraizes.m suggest that you actually want to have it as a function file only. In that case, you should drop those printf's (replace them with comments and they will be displayed when you run help nraizes) so that the first statement is the actual function definition.
Related
I am trying to read 5x^2 but octave says that it's wrong also it allows us to put (sin(x/2))^3
clc; close all; clear;
pkg load symbolic;
syms x;
f=input("Introduce la funcion ");
diff(f,x)
also there is the output with both cases
case (sin(x/2))^3
Introduce la funcion (sin(x/2))^3
ans = (sym)
2/x\ /x\
3*sin |-|*cos|-|
\2/ \2/
----------------
2
case 5x^2
Introduce la funcion 5x^2
parse error:
syntax error
>>> 5x^2
^
error: called from
symbolic at line 6 column 2
I have a function in Julia that requires to do things in a loop. A parameter is passed to the loop, and the bigger this parameter, the slower the function gets. I would like to have a message to know in which iteration it is, but it seems that Julia waits for the whole function to be finished before printing anything. This is Julia 1.4. That behaviour was not on Julia 1.3.
A example would be like this
function f(x)
rr=0.000:0.0001:x
aux=0
for r in rr
print(r, " ")
aux+=veryslowfunction(r)
end
return aux
end
As it is, f, when called, does not print anything until it has finished.
You need to add after the print command:
flush(stdout)
Explanation
The standard output of a process is usually buffered. The particular buffer size and behavior will depend on your system setting and perhaps the terminal type.
By flushing the buffer you make sure that the contents is actually sent to the terminal.
Alternatively, you can also use a library like ProgressLogging.jl (needs TerminalLoggers.jl to see actual output), or ProgressMeter.jl, which will automatically update a nicely formatted status bar during each step of the loop.
For example, with ProgressMeter, a call to
function f(x)
rr=0.000:0.0001:x
aux=0
#showprogress for r in rr
aux += veryslowfunction(r)
end
return aux
end
will show something like (in the end):
Progress: 100%|██████████████████████████████████████████████████████████████| Time: 0:00:10
Again I can't reproduce the behaviour in my terminal (it always prints), but I wanted to add that for these types of situations the #show macro is quite neat:
julia> function f(x)
rr=0.000:0.0001:x
aux=0
for r in rr
#show r
aux+=veryslowfunction(r)
end
return aux
end
f (generic function with 1 method)
julia> f(1)
r = 0.0
r = 0.0001
r = 0.0002
...
It uses println under the hood:
julia> using MacroTools
julia> a = 5
5
julia> prettify(#expand(#show a))
quote
Base.println("a = ", Base.repr($(Expr(:(=), :ibex, :a))))
ibex
end
here is my problem. I'm trying to solve a system of two differential equations thanks to the two functions below. The part of the code that give me some trouble is the variable "rho". "rho" is a function which values are given from a file and that I tried to put in the the variable rho.
function [xdot]=f2(x,t)
# Parameters of the equations
t=[1:1:35926];
x = dlmread('data_txt.txt');
rho=x(:,4);
beta = 0.68*10^-2;
g = 1.5;
l = 1.6;
# Definition of the system of 2 ODE's :
xdot(1) = ((rho-beta)/g)*x(1) + l*x(2);
xdot(2) = (beta/g)*x(1)-l*x(2);
endfunction
.
# Initial conditions for the two variables :
x0 = [0;1];
# Definition of the time-vector -> (initial time,temporal mesh,final time) :
t = linspace (1, 10, 10000);
# Resolution with the lsode routine :
x = lsode ("f2", x0, t);
# Plot of the two curves :
plot (t,x);
When I run my code, I get the following error:
>> resolution_effective2
error: f2: A(I) = X: X must have the same size as I
error: called from
f2 at line 34 column 9
resolution_effective2 at line 8 column 3
error: lsode: evaluation of user-supplied function failed
error: called from
resolution_effective2 at line 8 column 3
error: lsode: inconsistent sizes for state and derivative vectors
error: called from
resolution_effective2 at line 8 column 3
I know that my error comes from a mismatch of size between some variable but I have been looking for the error for days now and I don't see. Could someone try to give and explain me an effective correction ?
Thank you
The error might come from your function f2. Its first argument x should have the same dimension as x0 since x0 is the initial condition of x.
In your case, whatever you intent to be the first argument of f2 is ignored since in your function you do x = dlmread('data_txt.txt'); this seems to be a mistake.
Then, xdot(1) = ((rho-beta)/g)*x(1) + l*x(2); will be a problem since rho is a vector.
You need to check the dimensions of x and rho.
I am trying to solve a system of two ODEs using Octave, and in particular the function lsode.
The code is the following:
function xdot = f (x,t)
a1=0.00875;
a2=0.075;
b1=7.5;
b2=2.5;
d1=0.0001;
d2=0.0001;
g=4*10^(-8);
K1=5000;
K2=2500;
n=2;
m=2;
xdot = zeros(2,1);
xdot(1) = a1+b1*x(1)^n/(K1^n+x(1)^n)-g*x(1)*x(2)-d1*x(1);
xdot(2) = a2+b2*x(1)^m/(K2^m+x(1)^m)-d2*x(2);
endfunction
t = linspace(0, 5000, 200)';
x0 = [1000; 1000];
x = lsode ("f", x0, t);
set term dumb;
plot(t,x);
I am getting continuously the same error, that "x" is not defined, and I do not know why. The error is the following:
warning: function name 'f' does not agree with function file name '/home /Simulation 1/sim.m'
error: 'x' undefined near line 17 column 17
error: called from
sim at line 17 column 9
It would we great that any of you could help me with this code.
You have two errors. One, you are not saving your source code with the proper name. Two, variable "x" is a vector, and nothing in your script indicates that. You should add a line "x = zeros(1,2);" right after "xdot = zeros(2,1);".
Try the following code:
function ODEs
t = linspace(0, 5000, 200);
x0 = [1000; 1000];
x = lsode (#f, x0, t);
fprintf('t = %e \t\t x = %e\n',t,x);
endfunction
function xdot = f(x,t)
a1=0.00875;
a2=0.075;
b1=7.5;
b2=2.5;
d1=0.0001;
d2=0.0001;
g=4*10^(-8);
K1=5000;
K2=2500;
n=2;
m=2;
xdot = zeros(2,1);
x = zeros(1,2);
xdot(1) = a1+b1*x(1)^n/(K1^n+x(1)^n)-g*x(1)*x(2)-d1*x(1);
xdot(2) = a2+b2*x(1)^m/(K2^m+x(1)^m)-d2*x(2);
endfunction
Save it as ODEs.m and execute it. It does not plot anything, but gives you an output with the results for the t range you supplied.
I am new to Octave although I can say I am an expert Matlab user. I am running Octave on a Linux server (Red Hat) remotely through PuTTY, from a windows machine.
I am observing a very strange behavior in Octave. I call myfun(a) which performs as expected giving the sought results. Now, if I run, say, myfun(b) with b!=a, I get again myfun(a). Clear -f does not solve the problem. I need to reboot octave to change the parameters.
What am I doing wrong?
Thanks a lot
Francesco
This is the code for the function I mentioned:
function [a, v, obj, infos, iter] = mle_garch( p )
#{
% this function estimates the GARCH(1,1) parameters
% it is assumed we pass the adjusted price level p
#}
global y = (diff(log(p))-mean(diff(log(p))))*100;
global h = zeros(size(y));
a0 = [var(y)*0.9; 0.8; 0.1];
[a, obj, infos, iter] = sqp(a0, #loglike_garch, [], #loglike_con, [], [], 1000);
v = sqrt(h * 260);
endfunction
function g = loglike_garch( a )
global y h
n = length(y);
h(1) = var(y);
for i = 2 : n,
h(i) = a(1) + a(2) * h(i-1) + a(3) * y(i-1)^2;
endfor
g = 0.5 * ( sum(log(h)) + sum(y.^2./h) ) / n;
endfunction
function f = loglike_con( a )
f = [1;0;0;0] + [0 -1 -1;eye(3)] * a;
endfunction
I'm assuming the myfun you mentioned is mle_garch. The problem is the way you're initializing the global h and v variables (do you really need them to be global?). When you have a piece of code like this
global y = (diff(log(p))-mean(diff(log(p))))*100;
global h = zeros(size(y));
the values of y and h are defined the first time only. You can change their values later on, but this specific lines will never be ran again. Since your code only uses the input argument to define these two variables, the value which you use to run the function the first time will be used every single other time. If you really want to keep those variables global, replace it with the following:
global y;
global h;
y = (diff(log(p))-mean(diff(log(p))))*100;
h = zeros(size(y));
But I don't see any reason to keep them global so just don't make them global.
Also, you mentioned this code worked fine in Matlab. I was under the impression that you couldn't initialize global and persistent variables in Matlab which would make your code illegal in Matlab.