I need to convert this code into C code.
Questions:
Will MATLAB Coder generate functions that have call by reference? Example foo(float* input, float* output) instead of float* output = foo(float* input)
function [U] = mpc (A, B, C, x, N, r, lb)
## Find matrix
PHI = phiMat(A, C, N);
GAMMA = gammaMat(A, B, C, N);
## Solve first with no constraints
U = solve(PHI, GAMMA, x, N, r, 0, 0, false);
## Then use the last U as upper bound
U = solve(PHI, GAMMA, x, N, r, lb, U(end), true);
end
function U = solve(PHI, GAMMA, x, N, r, lb, ub, constraints)
## Set U
U = zeros(N, 1);
## Iterate Gaussian Elimination
for i = 1:N
## Solve u
if(i == 1)
u = (r - PHI(i,:)*x)/GAMMA(i,i)
else
u = (r - PHI(i,:)*x - GAMMA(i,1:i-1)*U(1:i-1) )/GAMMA(i,i)
end
## Constraints
if(constraints == true)
if(u > ub)
u = ub;
elseif(u < lb)
u = lb;
end
end
## Save u
U(i) = u
end
end
function PHI = phiMat(A, C, N)
## Create the special Observabillity matrix
PHI = [];
for i = 1:N
PHI = vertcat(PHI, C*A^i);
end
end
function GAMMA = gammaMat(A, B, C, N)
## Create the lower triangular toeplitz matrix
GAMMA = [];
for i = 1:N
GAMMA = horzcat(GAMMA, vertcat(zeros((i-1)*size(C*A*B, 1), size(C*A*B, 2)),cabMat(A, B, C, N-i+1)));
end
end
function CAB = cabMat(A, B, C, N)
## Create the column for the GAMMA matrix
CAB = [];
for i = 0:N-1
CAB = vertcat(CAB, C*A^i*B);
end
end
My C-code. Yes its working!
/*
* Generalized_Predictive_Control.c
*
* Created on:
* Author:
*/
#include "Generalized_Predictive_Control.h"
/*
* Parameters
*/
int adim;
int ydim;
int rdim;
int horizon;
/*
* Deceleration
*/
static void obsv(float* PHI, const float* A, const float* C);
static void kalman(float* x, const float* A, const float* B, float* u, const float* K, float* y, const float* C);
static void mul(float* A, float* B, float* C, int row_a, int column_a, int column_b);
static void tran(float* A, int row, int column);
static void CAB(float* GAMMA, float* PHI, const float* A, const float* B, const float* C);
static void solve(float* GAMMA, float* PHI, float* x, float* u, float* r, float lb, float ub, int constraintsON);
static void print(float* A, int row, int column);
void GPC(int adim_, int ydim_, int rdim_, int horizon_, const float* A, const float* B, const float* C, const float* D, const float* K, float* u, float* r, float* y, float* x){
/*
* Set the dimensions
*/
adim = adim_;
ydim = ydim_;
rdim = rdim_;
horizon = horizon_;
/*
* Identify the model - Extended Least Square
*/
int n = 5;
float* phi;
float* theta;
//els(phi, theta, n, y, u, P);
/*
* Create a state space model with Observable canonical form
*/
/*
* Create the extended observability matrix
*/
float PHI[horizon*ydim*adim];
memset(PHI, 0, horizon*ydim*adim*sizeof(float));
obsv(PHI, A, C);
/*
* Create the lower triangular toeplitz matrix
*/
float GAMMA[horizon*rdim*horizon*ydim];
memset(GAMMA, 0, horizon*rdim*horizon*ydim*sizeof(float));
CAB(GAMMA, PHI, A, B, C);
/*
* Solve the best input value
*/
solve(GAMMA, PHI, x, u, r, 0, 0, 0);
solve(GAMMA, PHI, x, u, r, 0, *(u), 1);
/*
* Estimate the state vector
*/
kalman(x, A, B, u, K, y, C);
}
/*
* Identify the model
*/
static void els(float* P, float* phi, float* theta, int polyLength, int totalPolyLength, float* y, float* u, float* e){
/*
* move phi with the inputs, outputs, errors one step to right
*/
for(int i = 0; i < polyLength; i++){
*(phi + i+1 + totalPolyLength*0) = *(phi + i + totalPolyLength*0); // Move one to right for the y's
*(phi + i+1 + totalPolyLength*1) = *(phi + i + totalPolyLength*1); // Move one to right for the u's
*(phi + i+1 + totalPolyLength*2) = *(phi + i + totalPolyLength*2); // Move one to right for the e's
}
/*
* Add the current y, u and e
(*phi + totalPolyLength*0) = -*(y + 0); // Need to be negative!
(*phi + totalPolyLength*1) = *(u + 0);
(*phi + totalPolyLength*2) = *(e + 0);
*/
/*
* phi'*theta
*/
float y_est = 0;
for(int i = 0; i < totalPolyLength; i++){
y_est += *(phi + i) * *(theta + i);
}
float epsilon = *(y + 0) - y_est; // In this case, y is only one element array
/*
* phi*epsilon
*/
float phi_epsilon[totalPolyLength];
memset(phi_epsilon, 0, totalPolyLength*sizeof(float));
for(int i = 0; i < totalPolyLength; i++){
*(phi_epsilon + i) = *(phi + i) * epsilon;
}
/*
* P_vec = P*phi_epsilon
*/
float P_vec[totalPolyLength];
memset(P_vec, 0, totalPolyLength*sizeof(float));
mul(P, phi_epsilon, P_vec, totalPolyLength, totalPolyLength, 1);
/*
* Update our estimated vector theta = theta + P_vec
*/
for(int i = 0; i < totalPolyLength; i++){
*(theta + i) = *(theta + i) + *(P_vec + i);
}
/*
* Update P = P - (P*phi*phi'*P)/(1 + phi'*P*phi)
*/
// Create phi'
float phiT[totalPolyLength];
memset(phiT, 0, totalPolyLength*sizeof(float));
memcpy(phiT, phi, totalPolyLength*sizeof(float));
tran(phiT, totalPolyLength, 1);
// phi'*P
float phiT_P[totalPolyLength];
memset(phiT_P, 0, totalPolyLength*sizeof(float));
mul(phiT, P, phiT_P, 1, totalPolyLength, totalPolyLength);
// phi*phi'*P
float phi_phiT_P[totalPolyLength*totalPolyLength];
memset(phi_phiT_P, 0, totalPolyLength*totalPolyLength*sizeof(float));
mul(phi, phiT_P, phi_phiT_P, totalPolyLength, 1, totalPolyLength);
// P*phi*phi'*P
float P_phi_phiT_P[totalPolyLength*totalPolyLength];
memset(P_phi_phiT_P, 0, totalPolyLength*totalPolyLength*sizeof(float));
mul(P, phi_phiT_P, P_phi_phiT_P, totalPolyLength, totalPolyLength, totalPolyLength);
// P*phi
float P_phi[totalPolyLength];
memset(P_phi, 0, totalPolyLength*sizeof(float));
mul(P, phi, P_phi, totalPolyLength, totalPolyLength, 1);
// phi'*P*phi
float phiT_P_phi[1];
memset(phiT_P_phi, 0, 1*sizeof(float));
mul(phiT, P_phi, phiT_P_phi, 1, totalPolyLength, 1);
// P = P - (P_phi_phiT_P) / (1+phi'*P*phi)
for(int i = 0; i < totalPolyLength*totalPolyLength; i++){
*(P + i) = *(P + i) - *(P_phi_phiT_P + i) / (1 + *(phiT_P_phi));
}
}
/*
* This will solve if GAMMA is square!
*/
static void solve(float* GAMMA, float* PHI, float* x, float* u, float* r, float lb, float ub, int constraintsON){
/*
* Now we are going to solve on the form
* Ax=b, where b = (R*r-PHI*x) and A = GAMMA and x = U
*/
/*
* R_vec = R*r
*/
float R_vec[horizon*ydim];
memset(R_vec, 0, horizon*ydim*sizeof(float));
for(int i = 0; i < horizon*ydim; i++){
for (int j = 0; j < rdim; j++) {
*(R_vec + i + j) = *(r + j);
}
i += rdim-1;
}
/*
* PHI_vec = PHI*x
*/
float PHI_vec[horizon*ydim];
memset(PHI_vec, 0, horizon * ydim * sizeof(float));
mul(PHI, x, PHI_vec, horizon*ydim, adim, 1);
/*
* Solve now (R_vec - PHI_vec) = GAMMA*U
* Notice that this is ONLY for Square GAMMA with lower triangular toeplitz matrix e.g SISO case
* This using Gaussian Elimination backward substitution
*/
float U[horizon];
float sum = 0.0;
memset(U, 0, horizon*sizeof(float));
for(int i = 0; i < horizon; i++){
for(int j = 0; j < i; j++){
sum += *(GAMMA + i*horizon + j) * *(U + j);
}
float newU = (*(R_vec + i) - *(PHI_vec + i) - sum) / (*(GAMMA + i*horizon + i));
if(constraintsON == 1){
if(newU > ub)
newU = ub;
if(newU < lb)
newU = lb;
}
*(U + i) = newU;
sum = 0.0;
}
//print(U, horizon, 1);
/*
* Set last U to u
*/
if(constraintsON == 0){
*(u + 0) = *(U + horizon - 1);
}else{
*(u + 0) = *(U + 0);
}
}
/*
* Lower traingular toeplitz of extended observability matrix
*/
static void CAB(float* GAMMA, float* PHI, const float* A, const float* B, const float* C){
/*
* First create the initial C*A^0*B == C*I*B == C*B
*/
float CB[ydim*rdim];
memset(CB, 0, ydim*rdim*sizeof(float));
mul((float*)C, (float*)B, CB, ydim, adim, rdim);
/*
* Take the transpose of CB so it will have dimension rdim*ydim instead
*/
tran(CB, ydim, rdim);
/*
* Create the CAB matrix from PHI*B
*/
float PHIB[horizon*ydim*rdim];
mul(PHI, (float*) B, PHIB, horizon*ydim, adim, rdim); // CAB = PHI*B
tran(PHIB, horizon*ydim, rdim);
/*
* We insert GAMMA = [CB PHI;
* 0 CB PHI;
* 0 0 CB PHI;
* 0 0 0 CB PHI] from left to right
*/
for(int i = 0; i < horizon; i++) {
for(int j = 0; j < rdim; j++) {
memcpy(GAMMA + horizon*ydim*(i*rdim+j) + ydim*i, CB + ydim*j, ydim*sizeof(float)); // Add CB
memcpy(GAMMA + horizon*ydim*(i*rdim+j) + ydim*i + ydim, PHIB + horizon*ydim*j, (horizon-i-1)*ydim*sizeof(float)); // Add PHI*B
}
}
/*
* Transpose of gamma
*/
tran(GAMMA, horizon*rdim, horizon*ydim);
//print(CB, rdim, ydim);
//print(PHIB, rdim, horizon*ydim);
//print(GAMMA, horizon*ydim, horizon*rdim);
}
/*
* Transpose
*/
static void tran(float* A, int row, int column) {
float B[row*column];
float* transpose;
float* ptr_A = A;
for (int i = 0; i < row; i++) {
transpose = &B[i];
for (int j = 0; j < column; j++) {
*transpose = *ptr_A;
ptr_A++;
transpose += row;
}
}
// Copy!
memcpy(A, B, row*column*sizeof(float));
}
/*
* [C*A^1; C*A^2; C*A^3; ... ; C*A^horizon] % Extended observability matrix
*/
static void obsv(float* PHI, const float* A, const float* C){
/*
* This matrix will A^(i+1) all the time
*/
float A_pow[adim*adim];
memset(A_pow, 0, adim * adim * sizeof(float));
float A_copy[adim*adim];
memcpy(A_copy, (float*) A, adim * adim * sizeof(float));
/*
* Temporary matrix
*/
float T[ydim*adim];
memset(T, 0, ydim * adim * sizeof(float));
/*
* Regular T = C*A^(1+i)
*/
mul((float*) C, (float*) A, T, ydim, adim, adim);
/*
* Insert temporary T into PHI
*/
memcpy(PHI, T, ydim*adim*sizeof(float));
/*
* Do the rest C*A^(i+1) because we have already done i = 0
*/
for(int i = 1; i < horizon; i++){
mul((float*) A, A_copy, A_pow, adim, adim, adim); // Matrix power A_pow = A*A_copy
mul((float*) C, A_pow, T, ydim, adim, adim); // T = C*A^(1+i)
memcpy(PHI + i*ydim*adim, T, ydim*adim*sizeof(float)); // Insert temporary T into PHI
memcpy(A_copy, A_pow, adim * adim * sizeof(float)); // A_copy <- A_pow
}
}
/*
* x = Ax - KCx + Bu + Ky % Kalman filter
*/
static void kalman(float* x, const float* A, const float* B, float* u, const float* K, float* y, const float* C) {
/*
* Compute the vector A_vec = A*x
*/
float A_vec[adim*1];
memset(A_vec, 0, adim*sizeof(float));
mul((float*) A, x, A_vec, adim, adim, 1);
/*
* Compute the vector B_vec = B*u
*/
float B_vec[adim*1];
memset(B_vec, 0, adim*sizeof(float));
mul((float*) B, u, B_vec, adim, rdim, 1);
/*
* Compute the vector C_vec = C*x
*/
float C_vec[ydim*1];
memset(C_vec, 0, ydim*sizeof(float));
mul((float*) C, x, C_vec, ydim, adim, 1);
/*
* Compute the vector KC_vec = K*C_vec
*/
float KC_vec[adim*1];
memset(KC_vec, 0, adim*sizeof(float));
mul((float*) K, C_vec, KC_vec, adim, ydim, 1);
/*
* Compute the vector Ky_vec = K*y
*/
float Ky_vec[adim*1];
memset(Ky_vec, 0, adim*sizeof(float));
mul((float*) K, y, Ky_vec, adim, ydim, 1);
/*
* Now add x = A_vec - KC_vec + B_vec + Ky_vec
*/
for(int i = 0; i < adim; i++){
*(x + i) = *(A_vec + i) - *(KC_vec + i) + *(B_vec + i) + *(Ky_vec + i);
}
}
/*
* C = A*B
*/
static void mul(float* A, float* B, float* C, int row_a, int column_a, int column_b) {
// Data matrix
float* data_a = A;
float* data_b = B;
for (int i = 0; i < row_a; i++) {
// Then we go through every column of b
for (int j = 0; j < column_b; j++) {
data_a = &A[i * column_a];
data_b = &B[j];
*C = 0; // Reset
// And we multiply rows from a with columns of b
for (int k = 0; k < column_a; k++) {
*C += *data_a * *data_b;
data_a++;
data_b += column_b;
}
C++; // ;)
}
}
}
/*
* Print matrix or vector - Just for error check
*/
static void print(float* A, int row, int column) {
for (int i = 0; i < row; i++) {
for (int j = 0; j < column; j++) {
printf("%0.18f ", *(A++));
}
printf("\n");
}
printf("\n");
}
Disclaimer: I work on MATLAB Coder
There is a configuration setting to tell MATLAB Coder to generate code without using dynamically allocated memory or issue an error telling you why it can't do so.
cfg = coder.config('lib');
cfg.DynamicMemoryAllocation = 'Off';
codegen -config cfg ...
MATLAB Coder supports generating code with fixed-size arrays, variable-sized arrays, and dynamically allocated arrays. The various generated signature formats are shown in the documentation. For non-dynamically allocated variable-sized arrays, a common signature is something like: foo(x_data[100], x_size[2])
Yes, the generated code is generally portable and independent of MATLAB for the hardware you specify when generating code. The full list of available functions and classes supported for code generation is listed here. In a very small number of cases, the generated code needs to depend on libraries from MATLAB. Those cases will be called out in the documentation. Fundamental operations like horzcat and vertcat produce portable code that is independent of MATLAB.
Yes. For array outputs and MATLAB functions with multiple outputs, the generated code will return outputs by reference. It also supports passing an argument by reference in some cases when the corresponding MATLAB function has the same variable as an input and output: function A = foo(A,B) with a call like: y = foo(y,z); can produce something like void foo(double A[100], const double B[20]); where A is an input and output.