Chebyshev coefficients: Difference between revisions
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0.950 0.5816830895 0.5816830895 -8.98e-14
</pre>
=={{header|ALGOL 60}}==
{{works with|GNU Marst|Any - tested with release 2.7}}
{{Trans|ALGOL W}}...which is{{Trans|Java}}
<syntaxhighlight lang="algol60">
begin comment Chebyshev coefficients ;
real PI;
procedure chebyshevCoef( func, min, max, coef, N )
; value min, max, N
; real procedure func
; real min, max
; real array coef
; integer N
;
begin
real procedure map( x, min x, max x, min to, max to )
; value x, min x, max x, min to, max to
; real x, min x, max x, min to, max to
;
begin
map := ( x - min x ) / ( max x - min x ) * ( max to - min to ) + min to
end map ;
integer i, j;
for i := 0 step 1 until N - 1 do begin
real m, f;
m := map( cos( PI * ( i + 0.5 ) / N ), -1, 1, min, max );
f := func( m ) * 2 / N;
for j := 0 step 1 until N - 1 do begin
coef[ j ] := coef[ j ] + f * cos( PI * j * ( i + 0.5 ) / N )
end j
end i
end chebyshevCoef ;
PI := arctan( 1 ) * 4;
begin
integer N;
N := 10;
begin
real array c [ 0 : N - 1 ];
integer i;
chebyshevCoef( cos, 0, 1, c, N );
outstring( 1, "Coefficients:\n" );
for i := 0 step 1 until N - 1 do begin
if c[ i ] >= 0 then outstring( 1, " " );
outstring( 1, " " );outreal( 1, c[ i ] );outstring( 1, "\n" )
end i
end
end
end
</syntaxhighlight>
{{out}}
<pre>
Coefficients:
1.64716947539
-0.232299371615
-0.053715114622
0.00245823526698
0.000282119057434
-7.72222915635e-006
-5.89855645675e-007
1.15214277563e-008
6.59630183808e-010
-1.00219138544e-011
</pre>
=={{header|ALGOL 68}}==
{{Trans|Java}}... using nested procedures and returning the coefficient array instead of using a reference parameter.
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