eigenmath/coeff.cpp

119 lines
1.6 KiB
C++

#include "stdafx.h"
//-----------------------------------------------------------------------------
//
// Put polynomial coefficients on the stack
//
// Input: tos-2 p(x)
//
// tos-1 x
//
// Output: Returns number of coefficients on stack
//
// tos-n Coefficient of x^0
//
// tos-1 Coefficient of x^(n-1)
//
//-----------------------------------------------------------------------------
#include "defs.h"
void
coeff_cooked(void)
{
int h, i, n;
save();
p2 = pop();
p1 = pop();
h = tos;
if (p2 == nil) {
push(p1);
variables();
p2 = pop();
if (p2->u.tensor->nelem == 0) {
p2 = alloc_tensor(1);
p2->u.tensor->ndim = 1;
p2->u.tensor->dim[0] = 1;
p2->u.tensor->elem[0] = p1;
push(p2);
restore();
return;
}
push(p1);
push(p2->u.tensor->elem[0]);
} else {
push(p1);
push(p2);
}
coeff();
n = tos - h;
p1 = alloc_tensor(n);
p1->u.tensor->ndim = 1;
p1->u.tensor->dim[0] = n;
for (i = 0; i < n; i++)
p1->u.tensor->elem[i] = stack[i];
tos = h;
push(p1);
restore();
}
int
coeff(void)
{
int h, n;
save();
p2 = pop();
p1 = pop();
h = tos;
for (;;) {
push(p1); // FIXME faster to use evalat
push(p2);
push(zero);
subst();
eval();
p3 = pop();
push(p3);
push(p1);
push(p3);
subtract();
p1 = pop();
if (equal(p1, zero)) {
n = tos - h;
restore();
return n;
}
push(p1);
push(p2);
divide();
p1 = pop();
}
}
static char *s[] = {
"coeff(3*x^2+2*x+1)",
"(1,2,3)",
"coeff((x+1)*(y+1))",
"(1+y,1+y)",
"coeff((x+1)*(y+1),y)",
"(1+x,1+x)",
};
void
test_coeff(void)
{
test(__FILE__, s, sizeof s / sizeof (char *));
}