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Diffstat (limited to 'lib/laguerre.c')
| -rw-r--r-- | lib/laguerre.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/laguerre.c b/lib/laguerre.c new file mode 100644 index 0000000..b1e1284 --- /dev/null +++ b/lib/laguerre.c @@ -0,0 +1,62 @@ +// Laguerre +// +// laguerre +// +// Laguerre polynomial +// +// L_n(x) via recurrence relation +// +// Inputs: 2 +// Outputs: 1 +// Constants: 0 + + +#include <math.h> +#include "ts.h" + + +ts_parameter_t const ts_laguerre_p = { .n_inputs = 2, .n_outputs = 1, .n_constants = 0, .params_size = 0 }; + +uint_t ts_laguerre_offset( ts_constant_t const *c ) +{ + ( void )c; + return ( 0 ); +} + +int ts_laguerre( + fp_t * const *y, uint_t y_n, + fp_t const * const *x, uint_t x_n, + uint_t n, ts_constant_t const *c +) +{ + TS_PROLOGUE( ts_laguerre_p ); + (void)c; + for( uint_t i = 0; i < n; ++i ) + { + fp_t xv = x[0][i]; + if (x[1][i] < 0) { y[0][i] = 0; continue; } + uint_t n_val = (uint_t)x[1][i]; + if( n_val == 0 ) + { + y[0][i] = 1.0; + } + else if( n_val == 1 ) + { + y[0][i] = 1.0 - xv; + } + else + { + fp_t l0 = 1.0; + fp_t l1 = 1.0 - xv; + for( uint_t k = 2; k <= n_val; ++k ) + { + fp_t l2 = ((2.0 * (fp_t)k - 1.0 - xv) * l1 - (fp_t)(k - 1) * l0) / (fp_t)k; + l0 = l1; + l1 = l2; + } + y[0][i] = l1; + } + } + return 0; +} + |