I am trying to convert the following code from Trefethen's Spectral Methods in MATLAB to Python.
% p6.m - variable coefficient wave equation
% Grid, variable coefficient, and initial data:
N = 128; h = 2*pi/N; x = h*(1:N); t = 0; dt = h/4;
c = .2 + sin(x-1).^2;
v = exp(-100*(x-1).^2); vold = exp(-100*(x-.2*dt-1).^2);
% Time-stepping by leap frog formula:
tmax = 8; tplot = .15; clf, drawnow, set(gcf,'renderer','zbuffer')
plotgap = round(tplot/dt); dt = tplot/plotgap;
nplots = round(tmax/tplot);
data = [v; zeros(nplots,N)]; tdata = t;
for i = 1:nplots
for n = 1:plotgap
t = t+dt;
v_hat = fft(v);
w_hat = 1i*[0:N/2-1 0 -N/2+1:-1] .* v_hat;
w = real(ifft(w_hat));
vnew = vold - 2*dt*c.*w; vold = v; v = vnew;
end
data(i+1,:) = v; tdata = [tdata; t];
end
waterfall(x,tdata,data), view(10,70), colormap(1e-6*[1 1 1]);
axis([0 2*pi 0 tmax 0 5]), ylabel t, zlabel u, grid off
For the most part it is going smoothly except for this line of code
data = [v; zeros(nplots,N)]
After reading how to convert between Numpy and Matlab here Link I tried to convert it by doing the following
data = np.array(v,zeros(nplots,N))
but I get this error
data = np.array(v,zeros(nplots,N));
TypeError: data type not understood
Which I assume is because a numpy array has this structure
numpy.array(object,dtype=none)
I would appreciate any help with converting that line. Thank you in advance!
1条答案
按热度按时间yb3bgrhw1#
data = [v; zeros(nplots,N)]
这是连接两个矩阵并将它们堆叠起来,注意numpy中的;
,您可以使用numpy.concatenate((v, zeros((nplots,N))), axis = 0)
,其中axis是您要连接的轴,通过...基本上,当您调用
np.array
时,第一个参数必须是可迭代对象、列表、元组,而第二个参数必须是类型,即“int”、“float32”“float32”等等...但是您将类型设置为zeros(nplots,N)
numpy
却抱怨它不是类型...numpy.zeros
是相同的,第一个参数必须是元组,第二个参数必须是类型,很抱歉,我没有正确地包括()
它应该是
data = numpy.concatenate((v, numpy.zeros((nplots,N))), axis = 0)
,假设您要使用double
类型,这是标准类型。