* IntPower inverts the base first for negative exponents and multiplies then, resolves #34124

git-svn-id: trunk@39621 -

.gitattributes

@@ -16237,6 +16237,7 @@ tests/webtbs/tw33898.pp -text svneol=native#text/pascal
 tests/webtbs/tw3402.pp svneol=native#text/plain
 tests/webtbs/tw34021.pp -text svneol=native#text/pascal
 tests/webtbs/tw3411.pp svneol=native#text/plain
+tests/webtbs/tw34124.pp svneol=native#text/pascal
 tests/webtbs/tw3418.pp svneol=native#text/plain
 tests/webtbs/tw3423.pp svneol=native#text/plain
 tests/webtbs/tw3429.pp svneol=native#text/plain

rtl/objpas/math.pp

@@ -1021,8 +1021,8 @@ function lnxp1(x : float) : float;
       end;
   end;
 
-function power(base,exponent : float) : float;
 
+function power(base,exponent : float) : float;
   begin
     if Exponent=0.0 then
       result:=1.0
@@ -1034,6 +1034,7 @@ function power(base,exponent : float) : float;
       result:=exp(exponent * ln (base));
   end;
 
+
 function intpower(base : float;const exponent : Integer) : float;
   var
      i : longint;
@@ -1042,6 +1043,8 @@ function intpower(base : float;const exponent : Integer) : float;
        result:=1
      else
        begin
+         if exponent<0 then
+           base:=1.0/base;
          i:=abs(exponent);
          intpower:=1.0;
          while i>0 do
@@ -1054,8 +1057,6 @@ function intpower(base : float;const exponent : Integer) : float;
               i:=i-1;
               intpower:=intpower*base;
            end;
-         if exponent<0 then
-           intpower:=1.0/intpower;
        end;
   end;
 

tests/webtbs/tw34124.pp

@@ -0,0 +1,26 @@
+program intpow;
+{$apptype console}
+{$mode delphi}
+
+uses sysutils, math;
+var
+  x,d: double;
+begin
+{$ifdef FPC_HAS_TYPE_DOUBLE}
+  writeln('Spurious overflows in intpower');
+  try
+    d := 10;
+    x := intpower(d,-314);
+    writeln('10^(-314) = ',x); //should be 1e-315
+  except
+    on E: Exception do writeln('10^(-314) (should be 1e-314): ', E.Message);
+  end;
+  try
+    d := 2;
+    x := intpower(d,-2000);
+    writeln('2^(-2000) = ',x); //should be 0
+  except
+    on E: Exception do writeln(' 0.5^2000 (should be 0) : ', E.Message);
+  end;
+{$endif FPC_HAS_TYPE_DOUBLE}
+end.