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embeddedrungekutta.cpp
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Wed, Oct 2, 14:12
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Fri, Oct 4, 14:12 (1 d, 21 h)
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rSPECMICP SpecMiCP / ReactMiCP
embeddedrungekutta.cpp
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#include "catch.hpp"
#include "odeint/runge_kutta_step.hpp"
using
namespace
specmicp
::
odeint
;
void
rhs1
(
double
x
,
const
double
&
yin
,
double
&
yout
)
{
yout
=
-
2
*
yin
;
}
void
rhs2
(
double
x
,
const
vector_t
<
2
>&
y
,
vector_t
<
2
>&
yout
)
{
yout
(
0
)
=
y
(
1
);
yout
(
1
)
=
-
y
(
0
);
}
TEST_CASE
(
"Embedded Runge Kutta"
)
{
SECTION
(
"Simple test Cash-Karp"
)
{
CashKarpStep
<
1
>
algo
(
rhs1
,
butcher_cash_karp45
);
double
yout
,
yerr
;
double
tf
=
0.01
;
algo
.
run_step
(
1
,
-
2
,
0
,
tf
,
yout
,
yerr
);
CHECK
(
yout
==
Approx
(
std
::
exp
(
-
2
*
tf
)).
epsilon
(
1e-3
));
tf
=
0.05
;
algo
.
run_step
(
1
,
-
2
,
0
,
tf
,
yout
,
yerr
);
CHECK
(
yout
==
Approx
(
std
::
exp
(
-
2
*
tf
)).
epsilon
(
1e-2
));
}
SECTION
(
"Simple test Dormand-Prince"
)
{
DormandPrinceStep
<
1
>
algo
(
rhs1
,
butcher_dormand_prince45
);
double
yout
,
yerr
;
double
tf
=
0.005
;
algo
.
run_step
(
1
,
-
2
,
0
,
tf
,
yout
,
yerr
);
CHECK
(
yout
==
Approx
(
std
::
exp
(
-
2
*
tf
)).
epsilon
(
1e-3
));
tf
=
0.01
;
algo
.
run_step
(
1
,
-
2
,
0
,
tf
,
yout
,
yerr
);
CHECK
(
yout
==
Approx
(
std
::
exp
(
-
2
*
tf
)).
epsilon
(
1e-2
));
}
SECTION
(
"Spring Cash-Karp"
)
{
CashKarpStep
<
2
>
algo
=
get_cash_karp_step
<
2
>
(
rhs2
);
vector_t
<
2
>
yout
,
yerr
;
vector_t
<
2
>
y0
,
dydx
;
y0
<<
1
,
0
;
dydx
<<
0
,
-
1
;
double
tf
=
0.01
;
algo
.
run_step
(
y0
,
dydx
,
0
,
tf
,
yout
,
yerr
);
CHECK
(
yout
(
0
)
==
Approx
(
std
::
cos
(
tf
)).
epsilon
(
1e-3
));
}
SECTION
(
"Spring Dormand-Prince"
)
{
DormandPrinceStep
<
2
>
algo
=
get_dormand_prince_step
<
2
>
(
rhs2
);
vector_t
<
2
>
yout
,
yerr
;
vector_t
<
2
>
y0
,
dydx
;
y0
<<
1
,
0
;
dydx
<<
0
,
-
1
;
double
tf
=
0.01
;
algo
.
run_step
(
y0
,
dydx
,
0
,
tf
,
yout
,
yerr
);
CHECK
(
yout
(
0
)
==
Approx
(
std
::
cos
(
tf
)).
epsilon
(
1e-3
));
}
SECTION
(
"Adaptative test Cash-Karp"
)
{
CashKarpStep
<
1
>
algo
=
get_cash_karp_step
<
1
>
(
rhs1
);
vector_t
<
1
>
yout
,
dydx
;
yout
=
1
;
dydx
=
-
2
;
StepLength
stepl
(
0.5
);
double
x
=
0.0
;
int
cnt
=
0
;
while
(
x
<
5
)
{
algo
.
rk_step
(
yout
,
dydx
,
x
,
stepl
);
cnt
+=
1
;
CHECK
(
yout
==
Approx
(
std
::
exp
(
-
2
*
x
)).
epsilon
(
1e-3
));
stepl
.
get_next
();
algo
.
get_rhs
(
x
,
yout
,
dydx
);
}
}
SECTION
(
"Adaptative test Dormand-Prince"
)
{
DormandPrinceStep
<
1
>
algo
=
get_dormand_prince_step
<
1
>
(
rhs1
);
vector_t
<
1
>
yout
,
dydx
;
yout
=
1
;
dydx
=
-
2
;
StepLength
stepl
(
0.5
);
double
x
=
0.0
;
int
cnt
=
0
;
while
(
x
<
5
)
{
algo
.
rk_step
(
yout
,
dydx
,
x
,
stepl
);
cnt
+=
1
;
CHECK
(
yout
==
Approx
(
std
::
exp
(
-
2
*
x
)).
epsilon
(
1e-3
));
stepl
.
get_next
();
algo
.
get_rhs
(
x
,
yout
,
dydx
);
}
}
SECTION
(
"Cosine adaptative test - Cash-Karp"
)
{
CashKarpStep
<
2
>
algo
=
get_cash_karp_step
<
2
>
(
rhs2
);
vector_t
<
2
>
yout
,
dydx
;
yout
<<
1
,
0
;
dydx
<<
0
,
-
1
;
StepLength
stepl
(
0.5
);
double
x
=
0.0
;
int
cnt
=
0
;
while
(
x
<
4
)
{
algo
.
rk_step
(
yout
,
dydx
,
x
,
stepl
);
cnt
+=
1
;
CHECK
(
yout
(
0
)
==
Approx
(
std
::
cos
(
x
)).
epsilon
(
1e-3
));
stepl
.
get_next
();
algo
.
get_rhs
(
x
,
yout
,
dydx
);
}
}
}
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