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(too long for a comment)

Plot[{ColorData["VisibleSpectrum"][x][[1]],
      ColorData["VisibleSpectrum"][x][[2]],
      ColorData["VisibleSpectrum"][x][[3]]}, {x, 380, 750}, PlotStyle -> {Red, Green, Blue}]

It doesn't seem that you'll be able to obtain Yellow (RGBColor[1, 1, 0]) from ColorData["VisibleSpectrum"]; unfortunately, the docs say nothing about how they're blending the colors to produce "VisibleSpectrum".

Addendum:

Just to make this post less useless, here's a Mathematica implementation of Bruton's conversion algorithm:

brutonIntensity = Interpolation[{{380, 3/10}, {420, 1}, {700, 1}, {780, 3/10}},
                                InterpolationOrder -> 1];

brutonLambda[x_, γ_: 4/5] := Map[N[brutonIntensity[x] #]^γ &, 
    Blend[{{0, Magenta}, {3/20, Blue}, {11/40, Cyan}, {13/40, Green}, {1/2, Yellow},
           {53/80, Red}, {1, Red}}, Rescale[x, {380, 780}]]] /;
    380 <= x <= 780 && 0 < γ <= 1

Here's a gradient plot:

and an RGB component plot:

For converting wavelengths to CIE xyz coordinates, see this thread; the current version of Mathematica now has built-in (but undocumented) functionality for the CIE CMFs. Alternatively, I also posted serviceable approximations of the CMFs as well in there.

(too long for a comment)

Plot[{ColorData["VisibleSpectrum"][x][[1]],
      ColorData["VisibleSpectrum"][x][[2]],
      ColorData["VisibleSpectrum"][x][[3]]}, {x, 380, 750}, PlotStyle -> {Red, Green, Blue}]

It doesn't seem that you'll be able to obtain Yellow (RGBColor[1, 1, 0]) from ColorData["VisibleSpectrum"]; unfortunately, the docs say nothing about how they're blending the colors to produce "VisibleSpectrum".

Addendum:

Just to make this post less useless, here's a Mathematica implementation of Bruton's conversion algorithm:

brutonIntensity = Interpolation[{{380, 3/10}, {420, 1}, {700, 1}, {780, 3/10}},
                                InterpolationOrder -> 1];

brutonLambda[x_, γ_: 4/5] := Map[N[brutonIntensity[x] #]^γ &, 
    Blend[{{0, Magenta}, {3/20, Blue}, {11/40, Cyan}, {13/40, Green}, {1/2, Yellow},
           {53/80, Red}, {1, Red}}, Rescale[x, {380, 780}]]] /;
    380 <= x <= 780 && 0 < γ <= 1

Here's a gradient plot:

and an RGB component plot:

For converting wavelengths to CIE xyz coordinates, see this thread; the current version of Mathematica now has built-in (but undocumented) functionality for the CIE CMFs. Alternatively, I also posted serviceable approximations of the CMFs as well in there.

(too long for a comment)

Plot[{ColorData["VisibleSpectrum"][x][[1]],
      ColorData["VisibleSpectrum"][x][[2]],
      ColorData["VisibleSpectrum"][x][[3]]}, {x, 380, 750}, PlotStyle -> {Red, Green, Blue}]

It doesn't seem that you'll be able to obtain Yellow (RGBColor[1, 1, 0]) from ColorData["VisibleSpectrum"]; unfortunately, the docs say nothing about how they're blending the colors to produce "VisibleSpectrum".

Addendum:

Just to make this post less useless, here's a Mathematica implementation of Bruton's conversion algorithm:

brutonIntensity = Interpolation[{{380, 3/10}, {420, 1}, {700, 1}, {780, 3/10}},
                                InterpolationOrder -> 1];

brutonLambda[x_, γ_: 4/5] := Map[N[brutonIntensity[x] #]^γ &, 
    Blend[{{0, Magenta}, {3/20, Blue}, {11/40, Cyan}, {13/40, Green}, {1/2, Yellow},
           {53/80, Red}, {1, Red}}, Rescale[x, {380, 780}]]] /;
    380 <= x <= 780 && 0 < γ <= 1

Here's a gradient plot:

and an RGB component plot:

I haven't fully investigated the method for converting wavelengths to CIE xyz coordinates; maybe one of these days...

(too long for a comment)

Plot[{ColorData["VisibleSpectrum"][x][[1]],
      ColorData["VisibleSpectrum"][x][[2]],
      ColorData["VisibleSpectrum"][x][[3]]}, {x, 380, 750}, PlotStyle -> {Red, Green, Blue}]

It doesn't seem that you'll be able to obtain Yellow (RGBColor[1, 1, 0]) from ColorData["VisibleSpectrum"]; unfortunately, the docs say nothing about how they're blending the colors to produce "VisibleSpectrum".

Addendum:

Just to make this post less useless, here's a Mathematica implementation of Bruton's conversion algorithm:

brutonIntensity = Interpolation[{{380, 3/10}, {420, 1}, {700, 1}, {780, 3/10}},
                                InterpolationOrder -> 1];

brutonLambda[x_, γ_: 4/5] := Map[N[brutonIntensity[x] #]^γ &, 
    Blend[{{0, Magenta}, {3/20, Blue}, {11/40, Cyan}, {13/40, Green}, {1/2, Yellow},
           {53/80, Red}, {1, Red}}, Rescale[x, {380, 780}]]] /;
    380 <= x <= 780 && 0 < γ <= 1

Here's a gradient plot:

and an RGB component plot:

For converting wavelengths to CIE xyz coordinates, see this thread; the current version of Mathematica now has built-in (but undocumented) functionality for the CIE CMFs. Alternatively, I also posted serviceable approximations of the CMFs as well in there.

(too long for a comment)

Plot[{ColorData["VisibleSpectrum"][x][[1]],
      ColorData["VisibleSpectrum"][x][[2]],
      ColorData["VisibleSpectrum"][x][[3]]}, {x, 380, 750}, PlotStyle -> {Red, Green, Blue}]

It doesn't seem that you'll be able to obtain Yellow (RGBColor[1, 1, 0]) from ColorData["VisibleSpectrum"]; unfortunately, the docs say nothing about how they're blending the colors to produce "VisibleSpectrum".

(too long for a comment)

Plot[{ColorData["VisibleSpectrum"][x][[1]],
      ColorData["VisibleSpectrum"][x][[2]],
      ColorData["VisibleSpectrum"][x][[3]]}, {x, 380, 750}, PlotStyle -> {Red, Green, Blue}]

It doesn't seem that you'll be able to obtain Yellow (RGBColor[1, 1, 0]) from ColorData["VisibleSpectrum"]; unfortunately, the docs say nothing about how they're blending the colors to produce "VisibleSpectrum".

Addendum:

Just to make this post less useless, here's a Mathematica implementation of Bruton's conversion algorithm:

brutonIntensity = Interpolation[{{380, 3/10}, {420, 1}, {700, 1}, {780, 3/10}},
                                InterpolationOrder -> 1];

brutonLambda[x_, γ_: 4/5] := Map[N[brutonIntensity[x] #]^γ &, 
    Blend[{{0, Magenta}, {3/20, Blue}, {11/40, Cyan}, {13/40, Green}, {1/2, Yellow},
           {53/80, Red}, {1, Red}}, Rescale[x, {380, 780}]]] /;
    380 <= x <= 780 && 0 < γ <= 1

Here's a gradient plot:

and an RGB component plot:

I haven't fully investigated the method for converting wavelengths to CIE xyz coordinates; maybe one of these days...