Convert matlab struct to C struct for mex

Question

Nicholas 2014-7-24

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/143251-convert-matlab-struct-to-c-struct-for-mex

编辑： Nicholas 2014-7-24

I have a struct that I'm writing in C and need to use a mex function to use it in matlab. The struct was originally in matlab and need to have the variables:

force = feval(forcing, Euler, Euler.x(:,k));
q     = squeeze(q(:,k,:));
q0    = squeeze(Euler.q0(:,k,:));
nx    = Euler.nx(:,k);% normal vector
J     = Euler.J(1,k);
rx    = Euler.rx(1,k);
qh    = reshape(qh(k:k+1,:),[],1);
k     = k;

The mex function I have come up with is:

#include "mex.h"
/* Extract local info for element k */
/* local struct */
typedef struct
{
    double force;
    double q;
    double q0;
    double nx;
    double J;
    double rx;
    double qh;
    double k;
} LocalInfo;
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
  mxArray *field;
  LocalInfo Local;
    field = mexGetVariable(const char global,const char force);
    Local.force = mxGetScalar(field);
    field = mexGetVariable(const char global,const char q);
    Local.q = mxGetScalar(field);
    field = mexGetVariable(const char global,const char q0);
    Local.q0 = mxGetScalar(field);
    field = mexGetVariable(const char global,const char nx);
    Local.nx = mxGetScalar(field);
    field = mexGetVariable(const char global,const char J);
    Local.J = mxGetScalar(field);
    field = mexGetVariable(const char global,const char rx);
    Local.rx = mxGetScalar(field);
    field = mexGetVariable(const char global,const char qh);
    Local.qh = mxGetScalar(field);
    field = mexGetVariable(const char global,const char k);
    Local.k = mxGetScalar(field);
}

I don't think I'm using the mexGetVariable right, but I haven't used it before and can't figure it out.

The forcing function in the matlab part is:

function [f] = forcing(Euler, x)
% Compute the forcing to yield exact solution
% $$$ rhoExact = @(x,t) 1 + A * sin(pi * (x - t));
% $$$ if (Euler.forcingFlag ~= 1
% $$$   uExact   = @(x,t) ones(size(x));
% $$$ else
% $$$   uExact   = @(x,t) x;
% $$$ end
% $$$ pExact   = @(x,t) ones(size(x));
% $$$ EnerExact = @(x,t)  pExact(x,t)/gamm1 + ...
% $$$     0.5 * rhoExact(x,t) .* uExact(x,t).^2;
if Euler.forcingFlag == 1,
    A     = Euler.A;
    t     = Euler.time;
    gamm1 = Euler.gamm1;
    r    = 1 + A * sin(pi * (x - t));
    dr_t = -pi * A * cos(pi*(x-t));
    dr_x =  pi * A * cos(pi*(x-t));
    u    = x*1.e-4;
    du_t = 0;
    du_x = 1*1.e-4;
    p    = 1;
    dp_t = 0;
    dp_x = 0;
    E    = p / gamm1 + 0.5 * r .* u.^2;
    dE_t = dp_t / gamm1 + 0.5 * dr_t .* u.^2 + r .* u .* du_t;
    dE_x = dp_x / gamm1 + 0.5 * dr_x .* u.^2 + r .* u .* du_x;
    fluxr  = r .* u;
    dfluxr_t = dr_t .* u + r .* du_t;
    dfluxr_x = dr_x .* u + r .* du_x;
    fluxru   = r .* u.^2 + p;
    dfluxru_x = dr_x .* u.^2 + 2 * r .* u .* du_x + dp_x;
    fluxE   = (E + p) .* u;
    dfluxE_x = (dE_x + dp_x) .* u + (E + p) .* du_x;
    f = zeros(size(x,1),3);
    f(:,1) = dr_t + dfluxr_x;
    f(:,2) = dfluxr_t + dfluxru_x;
    f(:,3) = dE_t + dfluxE_x;
else
  f = zeros(size(x,1),3);
end