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* patch by Rika: Improve SinH and TanH, resolves #40086

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florian 2023-01-04 19:04:40 +01:00
parent 96eb5da939
commit 9889a81062
1 changed files with 22 additions and 6 deletions
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28
rtl/objpas/math.pp
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@ -1281,8 +1281,10 @@ function sinh(x : Single) : Single;
temp : ValReal; temp : ValReal;
begin begin
temp:=exp(x); temp:=exp(x);
{ copysign ensures that sinh(-0.0)=-0.0 } { gives better behavior around zero, and in particular ensures that sinh(-0.0)=-0.0 }
sinh:=copysign(0.5*(temp-1.0/temp),x); if temp=1 then
exit(x);
sinh:=0.5*(temp-1.0/temp);
end; end;
{$ENDIF} {$ENDIF}
{$ifdef FPC_HAS_TYPE_DOUBLE} {$ifdef FPC_HAS_TYPE_DOUBLE}
@ -1291,8 +1293,9 @@ function sinh(x : Double) : Double;
temp : ValReal; temp : ValReal;
begin begin
temp:=exp(x); temp:=exp(x);
{ copysign ensures that sinh(-0.0)=-0.0 } if temp=1 then
sinh:=copysign(0.5*(temp-1.0/temp),x); exit(x);
sinh:=0.5*(temp-1.0/temp);
end; end;
{$ENDIF} {$ENDIF}
{$ifdef FPC_HAS_TYPE_EXTENDED} {$ifdef FPC_HAS_TYPE_EXTENDED}
@ -1301,8 +1304,9 @@ function sinh(x : Extended) : Extended;
temp : Extended; temp : Extended;
begin begin
temp:=exp(x); temp:=exp(x);
{ copysign ensures that sinh(-0.0)=-0.0 } if temp=1 then
sinh:=copysign(0.5*(temp-1.0/temp),x); exit(x);
sinh:=0.5*(temp-1.0/temp);
end; end;
{$ENDIF} {$ENDIF}
@ -1313,10 +1317,14 @@ function tanh(x : Single) : Single;
begin begin
if x < 0 then begin if x < 0 then begin
tmp:=exp(2*x); tmp:=exp(2*x);
if tmp=1 then
exit(x);
result:=(tmp-1)/(1+tmp) result:=(tmp-1)/(1+tmp)
end end
else begin else begin
tmp:=exp(-2*x); tmp:=exp(-2*x);
if tmp=1 then
exit(x);
result:=(1-tmp)/(1+tmp) result:=(1-tmp)/(1+tmp)
end; end;
end; end;
@ -1328,10 +1336,14 @@ function tanh(x : Double) : Double;
begin begin
if x < 0 then begin if x < 0 then begin
tmp:=exp(2*x); tmp:=exp(2*x);
if tmp=1 then
exit(x);
result:=(tmp-1)/(1+tmp) result:=(tmp-1)/(1+tmp)
end end
else begin else begin
tmp:=exp(-2*x); tmp:=exp(-2*x);
if tmp=1 then
exit(x);
result:=(1-tmp)/(1+tmp) result:=(1-tmp)/(1+tmp)
end; end;
end; end;
@ -1343,10 +1355,14 @@ function tanh(x : Extended) : Extended;
begin begin
if x < 0 then begin if x < 0 then begin
tmp:=exp(2*x); tmp:=exp(2*x);
if tmp=1 then
exit(x);
result:=(tmp-1)/(1+tmp) result:=(tmp-1)/(1+tmp)
end end
else begin else begin
tmp:=exp(-2*x); tmp:=exp(-2*x);
if tmp=1 then
exit(x);
result:=(1-tmp)/(1+tmp) result:=(1-tmp)/(1+tmp)
end; end;
end; end;